Filter cartridge for liquid filtration; assembly; and, methods

ABSTRACT

A liquid filter cartridge is provided. Preferred seal arrangements are provided, to provide for preferred axial load conditions, with respect to one or more of the end caps of the cartridge. Some cartridge configurations provided include no core structure or outer liner structure therein, to support axial load. Assemblies using the cartridge, and methods of assembly and use, are provided. The liquid filter cartridge can be a serviceable cartridge, or it can be retained permanently in a housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuing application of U.S. Ser. No.13/282,967, filed Oct. 27, 2011, now issued as U.S. Pat. No. 8,453,848.U.S. Ser. No. 13/282,967 is a continuing application of U.S. Ser. No.11/098,242 filed Apr. 4, 2005, which has now issued as U.S. Pat. No.8,167,142. The present application includes the disclosure of U.S. Ser.No. 13/282, 967; U.S. Ser. No. 11/098,242 and U.S. ProvisionalApplication 60/562,045 filed Apr. 13, 2004. The complete disclosures ofU.S. Ser. No. 13/282,967; U.S. Ser. No. 11/098,242 and U.S. Application60/562,045 filed Apr. 13, 2004 are incorporated herein by reference.Also a claim of priority to each of U.S. Ser. No. 13/282,967; U.S. Ser.No. 11/098,242 and U.S. Application 60/562,045 filed Apr. 13, 2004 ismade, to the extent appropriate.

FIELD OF THE DISCLOSURE

The present disclosure relates to liquid filters. It particularlyconcerns liquid filters which utilize a serviceable filter cartridgethat has a preferred seal arrangement and, in some instances, no axialload support liner. The liquid filters can be used for a variety ofapplications. Assemblies and methods of preparation and use areprovided.

BACKGROUND

Liquid filters are used for a variety of applications, for example tofilter lubricating fluids, fuels or hydraulic fluids. During use, liquidto be filtered is passed through a filter media, as filtration occurs. Awell-known configuration, is to position the filter media as a cylindersurrounding a central clean liquid volume, with filtration flowoccurring with an outside to inside (out-to-in) flow through the filtermedia. In other arrangements filtering flow is from inside the cartridgeto outside (in-to-out).

In many instances, the filter media is provided in the form of filtercartridge, in extension between first and second, opposite, end caps.Typically, the arrangement is also provided with a liner. For anout-to-in flow, an inner liner provides for both: (a) radial support ofthe media against collapse or damage, due to radial pressure duringnormal use; and (b) axial support against cartridge collapse and damage.Examples of filter cartridges which utilize such constructions, aredescribed for example in WO 02/070869 A1 published 12 Sep. 2002, (FIGS.1 and 2), the complete disclosure of WO 02/070869 being incorporatedherein by reference.

With an in-to-out flow, an outer liner can be used to provide mediaradial support and also axial support.

In many assemblies, the filter cartridge is constructed as a removableand replaceable (i.e., serviceable) component, see for example FIGS. 1and 2 of WO 02/070869 A1. It is desirable to provide for liquid filterdesigns that allow for desired options in construction of servicecartridges.

SUMMARY

According to the present disclosure, a liquid filter cartridge isprovided. A liquid filter cartridge generally has first and secondopposite end caps, with media extending therebetween. The media isconfigured to define an open central volume, which in use defines aninternal receiving volume for liquid. At least one of the end caps is anopen end cap, i.e., it has an aperture providing fluid flowcommunication with the internal volume. In some applications both endcaps are open end caps. In some embodiments, the liquid filter cartridgeis configured for out-to-in flow, during filtering; althoughalternatives (for in-to-out flow) are possible.

Preferred seal arrangements are provided for one or more of the endcaps. In preferred applications, the seal is provided at selectedlocations for advantageous net surface axial forces on one or more ofthe end caps, in use. In some applications a seal arrangement isprovided with respect to each end cap, in order to provide for apreferred level of surface axial force balance.

Example assemblies are provided. In addition methods of design, assemblyand use are described. Also, techniques for estimating the net axialsurface force operating on one or each end cap, in the overall filtercartridge, are provided. Also, some preferred seal configurations aredescribed and shown.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, side, cross-sectional view of a conventionalfilter cartridge.

FIG. 2 is a schematic top plan view of a portion of the filter cartridgeshown in FIG. 1.

FIG. 3 is a schematic, upper, side perspective view of a firstembodiment of a filter assembly according to the present disclosure.

FIG. 4 is a schematic, side cross-sectional view of the assemblydepicted in FIG. 3.

FIG. 5 is a schematic, fragmentary, enlarged view of a first portion ofFIG. 4.

FIG. 6 is a schematic view of a portion of a filter cartridge end cap.

FIG. 7 is a schematic view analogous to FIG. 6.

FIG. 8 is a schematic view analogous to FIG. 6.

FIG. 9 is a cross-sectional view of an alternate embodiment.

FIG. 10 is a schematic depiction useable to define terms used in FIG.11.

FIG. 11 is a graph showing the relationship between pleat number andpreferred seal location, for several different systems.

FIG. 12 is a cross-sectional view of an example filter cartridge.

FIG. 13 is a cross-sectional view of an assembly depicting the filtercartridge of FIG. 12 in a housing.

FIG. 14 is a graph showing relationship between Di and Do for a definedsystem.

FIG. 15 is a table showing calculated values for parameters, when othervariables are fixed, as shown.

FIG. 16 is a side cross-sectional view of another alternate embodiment.

FIG. 17 is a side cross-sectional view of still another alternateembodiment.

FIGS. 18-26 are plots of pleat cartridge definition and calculateddefinitions, in accord with the descriptions herein.

FIGS. 27, 29 and 31, are plots inner pleat diameter (Di) versus sealdiameter (Ds) for selected data, from FIGS. 18-26.

FIGS. 28, 30 and 32 are plots of outside diameter (Do) versus sealdiameter (Ds) for selected points of data in the tables of FIGS. 18-26.

DETAILED DESCRIPTION

In general, this disclosure relates to configurations of liquid filtercartridges and systems. In certain applications, the components of thefilter cartridge are provided in manners that allow for advantageousfilter cartridge integrity, during operation. In some instances, thetechniques are applied in filter cartridges which are serviceable withfilter cartridges, meaning they are removed from and replaced in filterassemblies during use. In other instances the filter cartridges aremaintained within the filter assemblies, and are changed out with thehousing component, as opposed to independently of a housing component.

Disclosed herein are general configurations and features that can beadvantageously applied, to accomplish such results. In addition, apresentation is made of theoretical principles underlying the advantagesachieved from preferred applications of the various mechanicalconfigurations shown, which can be applied in a variety of applicationsto accomplish similar, desirable, results.

In general, a serviceable filter cartridge is a filter cartridge that isremoved from, and is replaced in, a housing, during typical operation. Aliquid filter cartridge is generally a filter cartridge for filteringliquid. Typical ones include a cylindrical extension of filter mediaextending between opposite end caps. At least one of the end caps isgenerally an open end cap, allowing for flow therethrough of filteredliquid. In some instances, both end caps are open.

The filter media in such cartridges, is typically pleated. Indeed thetechniques described herein, are particularly adapted to arrangementswhich involve pleated media, although pleated media is not required inall instances. Further, in some instances media packs may includepleated media plus other types of media.

I. General Features of Liquid Filter Cartridges, Relating to StructuralIntegrity with Respect to Axial Forces

In association with FIGS. 1 and 2, a simplified model of a cartridgefilter is presented, to facilitate an understanding of principles of netsurface axial forces relevant to the present disclosure. In particular,reference numeral 1, of FIG. 1, depicts a filter cartridge. In general,filter cartridge 1 comprises filter media 3, for example pleated filtermedia 3 a arranged in a cylindrical or star pattern around a centralaxis 4. The media 3 extends between opposite end caps 5 and 6. End cap 5is an open end cap, 5 a, defining central aperture 8 for liquid flow outfrom interior 9. End cap 6, is a closed end cap 6 a, i.e., it has nocentral aperture therethrough. Herein, an end cap aperture which opensinto an inner volume surrounded by filter media, will generally becharacterized as an aperture in direct fluid flow communication with theinner volume. By the term “in direct fluid flow communication” it ismeant that liquid in the inner volume can pass directly through theaperture, without passing through filter media.

The liquid filter cartridge can be configured for either in-to-out flowor out-to-in flow. The term “out-to-in flow” in this context, is meantto refer to a liquid filter cartridge which is configured for liquidflow therethrough, from outside the cartridge to inside of thecartridge, as it passes through the filter media. An “in-to-out” flowliquid filter would have an opposite direction of flow during use.

The particular liquid filter cartridge 1 depicted, is an out-to-in flowliquid cartridge. Thus, during a filtering operation, liquid to befiltered generally passes through media 3 in the direction of arrows 10,from a region outside of cartridge 1 to interior 9. The filtered liquidthen passes out of cartridge 1 through aperture 8. For the cartridge 1depicted in FIG. 1, aperture 8 is lined by a radial seal arrangement 11,which can form a seal to an exit tube or similar structure. In theexample shown, the radial seal arrangement 11 will form a seal diameter(D_(s)) about the same as a diameter of aperture 8, and no greater thanan ID (internal diameter) of the media. Indeed the example seal diameter(D_(s)) shown will be slightly smaller than the media internal diameter(i.d. or Di) minus the thickness of liner 12. Herein the term “sealdiameter” (D_(s)) is meant to refer to the diameter of the seal surfacein engagement between the seal member and a housing component, such asan outlet tube. Thus, it is meant to refer to the operational sealdiameter, which may be slightly different from the diameter in theuninstalled component. The seal diameter (D_(s)) can be the diameter ofan inwardly directed seal or an outwardly directed seal, depending onthe system.

As the liquid filters through the media 3, contaminant material carriedwithin the liquid is deposited on or in the media 3. Thus, the media 3provides a barrier to liquid flow. Of course, in time media 3 willbecome occluded, and the filter cartridge 1 will need to be replaced inthe equipment of concern, i.e., serviced.

Herein the terms “axial,” “axial direction” and variants thereof, aregenerally meant to refer to forces directed generally in line with, orparallel to, a central longitudinal axis 4 of the cartridge 1identified; whereas the term “radial,” “radial forces” or similar termsare meant to refer to forces directed toward or away from such a centrallongitudinal axis 4.

As a result of the media 3 operating as a barrier, in general anupstream pressure (Pu) in a region upstream of the media is higher thanthe downstream pressure (Pd) in a region downstream side of the media.This means that, in use for out-to-in flow, the media 3 is under abiasing pressure radially toward the interior 9, i.e., in the directionof arrows 10. To support the media with respect to this, a radialsupport liner 12 is provided. The support liner 12 will typicallycomprise a perforated tube or an expanded metal tube.

Of course the seal arrangement 11, when element 1 is installed, alsoseparates regions subject to Pu from regions subject to Pd. The functionand purpose of the seal arrangement 11 is to provide for inhibition ofleakage of liquid between two such regions; specifically to preventfluid from getting into volume or interior 9 without passing throughfilter media 3.

The liner 12 provides an additional important support function. Thisfunction is an axial support function, inhibiting collapse or bucklingof the media 3 in an axial direction, between the end caps 5 and 6. Toevaluate this function, it is important to understand the net surfaceforces (axial) operating on the end caps.

Herein, in reference to an end cap, the term “outside” or “outsidesurface” is used to refer to a surface of the end cap which is directedaway from the media and away from the opposite end cap. Referring toFIG. 1, the outside surface of end cap 5 is indicated at 5 b, and theoutside surface of end cap 6 is indicated at 6 b. The inside surface ofan end cap, is generally the surface directed toward the media andtoward the opposite end cap. Thus, the inside surface of end cap 5 isindicated at 5 c, and the inside surface of end cap 6 is indicated at 6c.

A review of FIG. 2, leads to an understanding of the types of forcesthat cause axial stress on the cartridge 1. Specifically, FIG. 2 is atop plan view of end cap 5. In FIG. 2, pleated media 3 is depictedembedded in end cap 5, with a phantom line indicating the medialocation. For the particular embodiment shown in FIG. 2, media 3 isrepresented with only six pleats 21, for convenience. In a typicalarrangement, many more pleats (usually 8 to 12 per inch along theinside) will be present.

Again, the seal 11 and/or the media 3 separates an upstream regionsubject to pressure Pu from downstream area subject to pressure Pd,during use.

In FIG. 2, regions 25 generally depict portions of end cap 5 at whichboth the outside surface 5 b and the inside surface 5 c of the end cap 5are positioned upstream of the media 3. As a result, surface portions ofend cap 5 in region 25 are subjected to equal opposite pressures (Pu) onboth sides thereof. On the other hand, regions 26 are regions in whichthe outside surface 5 b of the end cap 5 is subjected to the upstreampressure (Pu), but the inside surface or underneath surface of the endcap 5 is positioned downstream of the media 3, and thus is subject to aninternal pressure Pd. Since Pu>Pd (and since force=pressure×area) inregion 26, there will generally be, during operation, pressures on endcap 26 which result in a net downward pressure (away from the viewer inFIG. 2, and in the direction of arrow 30, FIG. 1). Herein, the net axialforce operating on a selected end cap, due to liquid pressures againstthe opposite surfaces (outside and inside) thereof, will be referred toas the “net surface axial force” for the identified end cap. For end cap5 of FIGS. 1 and 2, the net surface axial force during use, is in thedirection of end cap 6.

A similar net force, but in an opposite (upward) direction, i.e., thedirection of arrow 31, FIG. 1, would be present for end cap 6, in use.It is noted, however, that in region 35, which is the center region ofend cap 6 where no aperture is present, additional force in thedirection of arrow 31 is provided, since there would be a pressuredifferential across this surface portion.

What is apparent from the schematic of FIGS. 1 and 2, and the abovediscussion, is that in a typical operation with a pressure differentialacross the media 3, end cap 5 will be under a net surface axial pressuretoward end cap 6, and end cap 6 will be under a net surface axialpressure in the general direction of end cap 5. In order to prevent themedia 3 from axially buckling or collapsing due to these forces, atypical filter cartridge such as cartridge 1 includes an axial load coreor liner 12, in axial extension between the end caps 5 and 6. Thisprovides axial strength in addition to the media 3, to inhibit mediacollapse.

In a typical arrangement, end caps 5 and 6 are either molded from amoldable plastic or polymeric material, or the end caps 5 and 6 comprisemetal, for example with media 3 potted or secured thereto by a sealantsuch as plastisol. In either case, the inner liner or core 12 istypically secured in the end caps at an appropriate position forproviding axial strength to the arrangement. Thus, the typical axialload liner 12 cannot be removed from the cartridge 1, without damagingto the filter cartridge 1 to allow for its removal. In such anarrangement the liner or core 12 will be said herein to be “integral”with a remainder of the filter cartridge or “permanently” included inthe filter cartridge.

As indicated in the background discussion above, if the filter assemblyuses a replaceable (or serviceable) filter cartridge, periodically thefilter cartridge 1 needs to be removed and replaced. If the filtercartridge is such as cartridge 1, FIG. 1, when the cartridge 1 isreplaced, so is the core 12. However, in general the inner liner 12 isconstructed of a material such as a perforated metal or rigid plastic orexpanded metal, that will not readily wear out. Thus, the replacement ofthe cartridge 1 periodically, with a liner 12 permanently positionedtherein, can lead to a waste of material that has not worn out in itslifetime of use. In addition, the inner core 12 can be problematic withrespect to disposal. For example, if it is manufactured from metal,incineration can be a problem. Also, the inner or liner core 12represents an expense, in assembly of the filter cartridge 1, that wouldbe avoided if possible. In addition, the presence of the liner 12 makesthe cartridge 5 more difficult to compress or compact during disposal.

Herein, a liner or core 12 which is permanently positioned within acartridge 5, at least in part in order to control axial load during use,will sometimes be referred to as an “axial load liner” or by similarterms. The term “axial load liner” is not meant to refer to all types ofliners that may be located on a side of the media. Wire or plastic netsor similar structures, that do not provide adequate axial strength tosignificantly resist significant axial loads, are not included withinthe term axial load liner. In general, if a liner is not adequatelystrong to resist an axial load of at least 20 lbs. applied thereto, itwill not be considered an axial load liner herein.

Still referring to FIG. 1, it is noted that if seals were located at ornear outer peripheral regions positions 37, 38, with an out-to-in flowarrangement, the general net forces would be such that the end caps 5, 6are biased away from one another. This principle is described, forexample, in U.S. Pat. No. 6,626,299.

II. General Principles Leading to Advantageous Constructions of LiquidFilter

The principles generally discussed in section I above, may be summarizedby the following considerations:

-   -   1. In general, each seal of the filter cartridge, and also the        media of a cartridge, separates surface portions of the two        opposite end caps into upstream regions, in which components are        subject to an operating pressure Pu, from downstream regions in        which components are subject to an operating pressure Pd. In        general, Pu>Pd.    -   2. The net axial surface forces acting upon a selected end cap        can be approximated by evaluating the amount of surface area        subject to Pu on each side of the end cap and the amount of area        subjected to Pd on each side of the end cap, since in general        force (F) is equal to pressure (P) times Area (A). In regions        where the same pressure is operating on the same area on        opposite sides of the end cap, there is no net directional        pressure that would affect the axial integrity of the media or        contribute to a net surface axial force for that end cap.    -   3. In a filter cartridge (out-to-in flow) having one open end        lined by an internal radial seal aligned with, or smaller than,        an ID or downstream edge of the media, and either an identical        opposite end cap or a closed opposite end cap, during operation        there is a net surface axial force for each end cap such that        each end cap is under pressure toward the other. An axial load        liner, which is contained within a conventional cartridge and        extends between the two end caps, provides structural integrity        by resisting this collapsing or buckling force.

In general, according to the principles of the present disclosure,preferred arrangements can be provided in which seal location is used toprovide desirable net surface axial forces on the end caps.

Optionally, this can be implemented in arrangements having no axial loadliners provided as a permanent part of the service part (i.e., thefilter cartridge).

A detailed discussion of the principles involved in selecting seallocation to accomplish these results, is provided in section IV below.Before the presentation of that section, several embodiments aredescribed which take advantage of, and demonstrate, the principles. Afeature of preferred embodiments is selection of the seal location(s) toprovide for no, or a desirably low level of, net surface axial pressuredifferential with respect to each end cap.

III. Balancing the Axial Forces to Achieve Preferred Arrangements; FIGS.3-5; FIG. 9

A. FIGS. 3-5.

The reference numeral 51, FIG. 3, generally designates a liquid filterassembly according to the present disclosure. Liquid filter assembly 51generally includes a filter head 53 and a filter housing 54. Theparticular liquid filter assembly 51 includes a removable andreplaceable (i.e., serviceable) filter cartridge 55 is positioned withinthe housing 54 (FIG. 4).

The liquid filter assembly 51 may be configured for a variety of liquidfilter operations; for example, as a lubricating oil filter, a hydraulicfluid filter or as fuel filter. The particular liquid filter assembly 51depicted is configured for use as oil filter assembly 58, with out-to-inflow. However, the basic principles described, and componentry shown,can be applied in the instance of other types of, or configurations of,liquid filters, including ones configured for in-to-out flow.

Referring to FIG. 4, during a normal filtering operation, liquid to befiltered enters the filter head 53 (from a flow circuit within theequipment) and passes through the filter head 53, via inlet channel 60.For a typical application, the channel 60 is configured to provide foran annular flow of inlet liquid. The liquid then flows into the housing54, specifically into annular region 62, surrounding cartridge 55between cartridge 55 and sidewall 54 a of housing 54. During filtering,the liquid flows through cartridge 55 and into central clean liquidvolume 66. The liquid then exits volume 66 in the direction of arrow 68,into an outlet flow channel 69, in filter head 53. The outlet flowchannel 69 would then provide fluid flow communication with appropriateequipment on which the filter head 53 is mounted. Such equipment couldinclude, for example, a vehicle, or various construction equipment orother equipment (stationary or mobile).

In a typical assembly, the housing 54 is openable. Referring to FIG. 4,in the instance of liquid filter assembly 51, the housing 54 is openableby separating the housing 54 from filter head 53, at threads 70. A seal71 to prevent leakage is provided by an o-ring.

Periodically, filter media 75, in filter cartridge 55, will becomeoccluded due to build up in (or on) the media 75 of contaminantsfiltered from the liquid flow. When the occlusion has reached anappropriately defined level, for example detected through pressuredifferential measurements or as a result of operation to a pre-definedservice interval, the media 75 is generally serviced, by replacement.Typically, service of media 75 is accomplished through removal andreplacement of serviceable cartridge 55.

The typical serviceable cartridge 55, generally comprises the media 75,positioned to extend between first and second, opposite, end caps 77,78. The end caps 77, 78 may be constructed from a variety of materials,for example they may be molded from a polymer or they may be configuredfrom metal, for example with the media secured thereto. For theparticular embodiment shown, the end caps 77, 78 are shown as molded endcaps made from an appropriate polymeric material.

In the arrangement shown, the media 75 is a pleated media cylinder 75 a,defining inner pleat tips or edges 75 b, and outer pleat tips or edges75 c, FIG. 5. The pleats extend axially, between the end caps 77, 78,FIG. 4.

For the particular arrangement shown, the filter cartridge 55 is a“double open end” filter cartridge 55 a. By this, it is meant that eachof the end caps 77, 78 is an “open” end cap 77 a, 78 a, each having acentral aperture (77 b, 78 b respectively) therethrough, positioned forfluid flow communication with central region 66.

A reason that the filter cartridge 55 is a “double open end” filtercartridge 55 a is that, during servicing, it is slid over support tube79. The support tube 79 is discussed in greater detail below. In theexample shown, support tube 79 remains affixed to the bowl or housing54, during a service operation in which the filter cartridge 55 isremoved and replaced. Of course in alternate systems, the support tubecould be constructed to not be permanently positioned in the housing.

Because the filter cartridge 55 is a serviceable component, toperiodically be removed and be replaced, it is necessary that a sealarrangement be provided, to ensure that there is no leakage ofunfiltered fluid into volume 66. For the particular embodiment depictedin FIG. 3, the seal arrangement comprises a first seal 82 and a secondseal 83. The first seal 82 is positioned for sealing between the end cap77 of cartridge 55 and portion 85 of filter head 53; and, the secondseal 83 is positioned to provide a seal between end cap 78 of thecartridge 55 and portion 86 a of housing 54.

In general, seal 82 comprises an o-ring 82 a, FIG. 5, mounted on anaxially directed seal support 82 b which extends axially outwardly fromend cap 77. Further, referring to FIG. 4, seal 83 comprises an analogouso-ring mounted on an axially directed extension, extending axiallyoutwardly, away from the media 75, from end cap 78.

In general, portion 85 of filter head 53, is an outside surface portionof a center liquid flow exit tube 85 a (FIG. 5); and, portion 86 a ofhousing 54 (FIG. 4) comprises a portion of a housing base 86. Outersidewall 54 a, of housing 54 projects (in the embodiment of FIGS. 3-5)upwardly toward filter head 53 from base 86. Inner liner, tube or core79 is secured to housing base 86.

A filter cartridge such as filter cartridge 55, FIGS. 4 and 5, will becharacterized herein as a “coreless cartridge,” since it contains (as anintegral component of the filter cartridge) no inner liner, tube orcore, to support axial load, secured permanently therein, in extensionbetween end caps 77, 78. It is noted that the term “coreless” in thiscontext is meant to refer to arrangements that do not have as anintegral part therein, an inner tubular support for axial load (asopposed to having no type of support at all). For example the mediacould have a pleated extension of light wire mesh or plastic mesh alongan inside thereof, and it would still be “coreless” in accord with thisdefinition. In general, if structure integral with the filter cartridgealong an inside of the media capable of supporting an axial compressiveload of at least 20 lbs. (9.1 kg), is not permanently present in thefilter cartridge, the filter cartridge will be considered “coreless” inaccord with this definition. The term “axial” in this context meaningforce in the direction of extension of axis 94, FIG. 4; i.e., adirection between the opposite end caps 77, 78.

It is noted that a filter cartridge will be considered “coreless” withinthe above definition, even if a core not permanently installed in thecartridge itself, is present elsewhere in the assembly 51.

Still referring to FIGS. 3-5, it will also be apparent that for thepreferred embodiment shown the filter cartridge 55 also includes nointegral outer support structure, to support axial load, extendingcontinuously between the end caps 77, 78. Such an arrangement will bereferred to herein as an “outer axial load liner free” filter cartridgeor as a filter cartridge with no axial load outer liner.

Herein a filter cartridge will be considered to have no outer axial loadliner or to be outer axial load liner free, even if it contains(integral with the filter cartridge) a pleated light mesh such as alight wire mesh or light plastic mesh or other structure around theoutside, that does not significantly resist compressive axial load.Herein, a filter cartridge will be considered to be outer axial loadliner free, as long as any outer liner present (integral with the filtercartridge) is not capable of supporting an axial load of at least 20 lbs(9.1 kg).

If the filter cartridge is both outer axial load liner free andcoreless, it may sometimes be referred to herein as “axial load linerfree.”

For the arrangements in FIGS. 4 and 5, support in this instance, bothradial and axial, for the media 75 of the filter cartridge 55 isprovided by inner core 79. The inner core 79 is a porous tubular member91, FIG. 5, positioned within liquid filter assembly 51 such that,during a service operation to replace the serviceable cartridge 55, theporous tubular member 91 is not removed and replaced. That is, theserviceable cartridge 55 is coreless, because the inner core 79 (i.e.,the porous tubular member 91) is not part of the filter cartridge 55.

For the particular embodiment shown, the inner core 79 is secured to aremainder of housing 54, FIG. 4. A particularly convenient method ofproviding for a secure fit, is to optionally use, as the tubular member91, FIG. 4, a member that is not radially continuous, but rather has agap or open seam 93, FIG. 5, therein. The particular seam 93 shown, isnot axial, but rather extends at an angle (A) to central axis 94, FIG. 5in accord with a similar liner (but integral the filter cartridge) shownin U.S. Pat. No. 6,206,205, the complete disclosure of which isincorporated herein by reference. The gap presented by seam 93 allowsthe perforated tubular member 91 to be radially compressed (underpressure) somewhat, to a smaller circumference, and thus it can besecured by press fit into a receiver 95 in base 86 of housing 54. Atypical gap will be selected to have an angle A of no more than 15°,preferably at least 0.5°, typically 1° to 15°.

For the particular assembly 51 depicted in FIGS. 4 and 5, the outsidediameter for the inner core 79 is selected such that cartridge 55 can beslid thereover, in use. Preferably the outside diameter of the support91 is of a size such that it will operate as an inner radial support tothe pleated media 75 a. In a typical application, to accomplish this,the OD of tubular support should preferably be chosen to be no more than0.09 inches (2.3 mm) from the ID of the inner pleat tips 75 b of pleatedmedia 75 a.

If desired, the porous tubular member 91 can be provided with bumps,ribs or other constructions on an outer surface thereof, to provide forcloser engagement to the inner pleat tips 75 b. The tubular member 91may comprise metal or a molded plastic.

In general, end cap 77 will be referred to herein as an “upper” end capsince in the normal installation position, FIG. 4, end cap 77 ispositioned directed upwardly. In contrast, end cap 78 will generally bereferred to herein as a lower or bottom end cap, since in a normalinstallation position of FIG. 4, it is directed downwardly.

End cap 78 can be configured to include a contaminant containment andcollection feature, not shown thereon. The contaminant containment andcollection feature may be according to PCT Publication WO 02/081052published Oct. 17, 2002, incorporated herein by reference.

Referring to FIG. 4, in order for liner 91 to provide for axial supportbetween end caps 77, 78, during a normal use, it is preferable toconstruct the filter cartridge 55, such that, between the end caps 77,78, (i.e., on the filter cartridge 55 as a whole, during use), there islittle or no net surface axial force on the element 55; and also suchthat there is little or no net surface axial force on each end cap 77,78.

If the filter cartridge 55 was constructed generally in accord with thecartridge 1, FIG. 1, except for both end caps being open, such a low netforce would not be created. This is because the net surface axial forceon end cap 5, FIG. 1, would be toward end cap 6; and, the net surfaceaxial force on end cap 6, FIG. 1, would be toward end cap 5.

In order to modify from this, preferred seal locations for end caps 77,78 are selected. It is the location of these seals, which will generatea preferred force profile at end cap 78, and will thus allow for littleor no net force on filter cartridge 55, or net surface force on each endcap 77, 78.

As indicated above, referring to FIGS. 4 and 5, the seal location forend cap 77 is at 82. As indicated above with respect to FIG. 4, the seallocation for end cap 78, is at 83. Herein the diameter of a seal isreferred to as Ds. The inside diameter defined by the pleats, will bereferred to as Di. The outside diameter defined by the pleat tips, willbe referred to as Do.

Herein the diameter of a seal which, for that end cap, provides for abalance of forces or a net axial surface force on that end cap, will bereferred to as Db or DsB.

From the discussions in Section II, it should be apparent that, for anend cap A, diameter DbA can be identified such that in normal use thesurface axial forces toward the outer surface of the end cap A and theinside surface of the end cap A are in balance. That is, a seal having adiameter DbA is one that would provide for no net surface axial forcesoperating on the associated end cap A, in use.

For an arrangement having two end caps, designated end cap A and end capB, if the seal in end cap A is located at DbA, and the seal at end cap Bis located at DbB, each end cap will be in balance with respect to netsurface axial forces, and there will be no net surface axial forceoperating on the associated cartridge. This would be the case even ifone of the end caps is closed, and thus does not require the seal toprotect against unfiltered liquid from entering the internal volume ofthe filter cartridge. That is, even with a closed end cap, a seal can beprovided engaging that end cap with a portion of the housing. This sealwould separate regions subjected to Pu from regions subjected to Pd.Thus, its location could be provided at a balance point Db. However thisunique latter seal would not be used to protect against unfiltered flowby-passing the media.

Again, herein, the diameter Ds of a seal which provides for a balance offorces against each surface of an associated end cap, is generallyreferred to as Db. An end cap A will be considered to be within apreferred level of balance, with respect to net axial surface forces,for a typical liquid filter cartridge, provided the seal diameter Ds isat a diameter within plus or minus 15% of DbA, i.e., within the range of0.85-1.15 DbA, inclusive. Typically, the seal diameter Ds is within therange of 0.9-1.1 DbA, inclusive, often 0.92-1.08 DbA. Most typically itwill be selected to be within the range of 0.95-1.05 DbA, inclusive. Asdiscussed below, the principles described herein can be applied outsideof these ranges, however.

The range stated is meant to indicate that in some instances axial loadsmay be accepted, which are not zero but rather are sufficiently small toaccommodate advantages structure as a result of axial loads acceptablefor the filter cartridge, under typical conditions of use expected.Although alternatives are possible, typically, the seal location will bepositioned outwardly from the inner pleat diameter (Di) at least 2 mm,often at least 5 mm, and sometimes at least 10 mm; and, also be at alocation recessed from the outer pleat diameter (Do) at least 2 mm,often at least 5 mm and sometimes at least 10 mm. Preferred locationscan be calculated for any given system, as discussed below.

In general, at least a first open end cap configured for fluid flow intoand out of the element, will have a seal diameter Ds as defined above.This would correspond to end cap 77, FIG. 3. Most preferably both endcaps (77, 78) have a seal diameter as defined above.

The principle of a balanced arrangement (seal(s) at Db) can be appliedin either a top load or a bottom load configuration. An example ofbottom load configuration utilizing these principles was provided inFIGS. 3-5.

Attention is now directed to FIG. 9. In FIG. 9 a liquid filterarrangement 200 is depicted, comprising a filter base 201 and aremovable cover 202. Secured within housing 203 formed by cover 202 andbase 201, is a filter cartridge 205. The filter cartridge 205 comprisespleated media 206 in extension between opposite end caps 207 and 208.End cap 207 is an open end cap, the radial seal indicated at 210 formedby an o-ring 211 mounted on an outwardly directed (relative to themedia) axial extension 212 of end cap 207.

At end cap 208 a seal 215 is shown formed by an o-ring 216 mounted on anoutwardly directed axial extension 217 of end cap 208.

It is noted that seal 210 is provided between o-ring 211 on end cap 207and a portion 220 of support liner 221. It is noted that seal 215 isformed between o-ring 216 on a portion of end cap 208, and a portion 225of base 203.

In use, service occurs by removing end cover 202, and then dislodgingelement 205 from its seal.

The assembly 200 is a top load arrangement, and includes a drainarrangement 230, to allow standing liquid to drain from interior 231, ascover 202 is being removed. General principles of such arrangements aredescribed in PCT Application US04/02074, filed Jan. 27, 2004,incorporated herein by reference.

Preferably seals 210 and 216 are each positioned at a location for abalanced seal diameter, Db (i.e., each is within 0.85-1.15 Db), inaccord with the above definitions.

IV. Methods for Evaluating Net Axial Forces Acting Upon an End CapArrangement of a Filter Cartridge; Approaches to Design

A. Background Principles

A mathematical method for estimating the net axial forces for any givenend cap or cartridge, is provided. In general the techniques areapplicable to a variety of sizes of liquid filter cartridges, which usepleated media. The various assumptions useable to support thecalculation are pointed out where appropriate.

Although liquid filter cartridges can be located in any positionrelative to gravity, for the sake of the simplicity, the concepts willbe discussed assuming an axis of the filter cartridge normal to theplane of the earth. Thus, in this section of the disclosure, forcesacting toward the earth (downward) will be defined as negative (−), andopposite forces as positive (+).

For initial purposes of this discussion, it will be assumed that thefilter cartridge is cylindrical, utilizes pleated media, and has endcaps which are circular.

FIG. 6 illustrates a portion of a filter cartridge. An end cap is shownat 400, and the pleated media at 401. The geometry of the pleated media401 is configured in a “V” shape. The arc A-B describes one completepleat. Pu is the upstream pressure and Pd is the downstream pressure.Because the thickness of the media 401 is small compared to the overallarea of media, it is assumed that the pressure drop across the mediaoccurs at the media centerline 402 and is a step function. Thisassumption means that the pressure on the upstream side of the media 401a is considered to remain constant through the first half of the mediathickness; and, that at a centerline of the media thickness the pressuredrops to that of the downstream pressure and remains constant throughthe last half of the media to the downstream side 401 b.

This idealization does not differ much from the actual pressuresituation significantly. However, this idealization of the pressure dropacross the media simplifies the mathematics related to defining thevarious surface areas on the end caps that are effected by the pressuredrop across the media. Also, it is assumed that the Pressures Pu and Pd,acting on the end cap surfaces, are uniform across those surfaces.

For the current model evaluated in FIGS. 6 and 7, it will be assumedthat the end cap 400 under consideration is an open end cap, having anoutside edge 404 and an inside edge 405 corresponding to the outer (Do)and inner (Di) pleat tips, respectively.

In FIG. 7, the illustration in FIG. 6 has been modified to calculate theareas effected by the pressure drop. A centerline 402 of the media 401is used rather than the full media thickness (as explained above). Au isthe area of the upper end cap 400 that is subject to the upstreampressure on both sides of the end cap 400. Because of this the pressureon both sides cancel each other out and do not contribute to the netsurface axial compressive force that is applied to the corresponding endcap or filter cartridge. Ad1+Ad2 is the combined area on the upper endcap that is subject to upstream pressure (Pu) on the outside surface ofthe end cap and to downstream pressure on the inside surface of the endcap. This combined area relates to one complete pleat. To know the totaleffect on the upper end cap, the number of pleats in the filtercartridge have to be used. Therefore the pressure drop across the filtercartridge creates a downward force equal to (Ad1+Ad2)×(pressuredrop)×(number of pleats).

The mathematics used to calculate Ad1 and Ad2 come from various appliedtrigonometric equations. An approach is to first find angle a, this canthen be used in an equation that will give us the combined area(Ad1+Ad3). Next is to find the combined area (Ad3+Ad4). By examinationof FIG. 7 one also knows from symmetry that:Ad ₃ =Ad ₄  (Eq.1)Finding ∠a°From FIG. 7 it can be shown that:Au+Ad ₁ +Ad ₂ +Ad ₃ +Ad ₄ =At∠a° is equal to one half of the entire angle that describes the area At.Since this area represents one cycle of pleats, the entire angle can befound by simply dividing 360° by the number of pleats. ∠a° is one halfof that.

$\begin{matrix}{{\angle\; a^{0}} = {\frac{360^{0}}{(2)\left( {P\; C} \right)} = \frac{180^{0}}{P\; C}}} & \left( {{Eq}.\mspace{14mu} 2} \right)\end{matrix}$Where PC is the Pleat Count (number of pleats in the entire filtercartridge).The area defined by Ad₁+Ad₃ is an oblique triangle with two sides knownand the included angle known. The equation for the area of this triangleaccording to Machinery's Handbook, 24th Edition, Page 83, second panelis:

$\begin{matrix}{{{A\; d_{1}} + {A\; d_{3}}} = {\left( \frac{Di}{2} \right)\left( \frac{Do}{2} \right)\left( \frac{{Sin}\;\angle\; a^{0}}{2} \right)}} & \left( {{Eq}.\mspace{14mu} 3} \right)\end{matrix}$Substituting Eq. 2 into Eq. 3 one gets:

$\begin{matrix}{{{A\; d_{1}} + {A\; d_{3}}} = {\left( \frac{Di}{8} \right)({Do})\left( {{Sin}\left( \frac{180^{0}}{PC} \right)} \right)}} & \left( {{Eq}.\mspace{14mu} 4} \right)\end{matrix}$Area Ad₃+Ad₄ can be defined by the equation for the area of a circularsector, from Machinery's Handbook, 24th Edition, p. 58:

${{A\; d_{3}} + {A\; d_{4}}} = {{.5}\left( \frac{Di}{2} \right)({Di})\left( \frac{\pi}{PC} \right)}$Reducing the equation down:

$\begin{matrix}{{{A\; d_{3}} + {A\; d_{4}}} = {\left( \frac{{Di}^{2}}{4} \right)\left( \frac{\pi}{P\; C} \right)}} & \left( {{Eq}.\mspace{14mu} 5} \right)\end{matrix}$Also, by symmetry we know that Ad₃=Ad₄. Eq. 5 then becomes:

$\begin{matrix}{{A\; d_{3}} = {\left( \frac{{Di}^{2}}{8} \right)\left( \frac{\pi}{P\; C} \right)}} & \left( {{Eq}.\mspace{14mu} 6} \right)\end{matrix}$Substituting Eq. 6 into Eq. 4 and solving for Ad₁:

$\begin{matrix}{{A\; d_{1}} = {\left( {\left( \frac{Di}{8} \right)({Do})\left( {{Sin}\left( \frac{180^{0}}{P\; C} \right)} \right)} \right) - \left( {\left( \frac{{Di}^{2}}{8} \right)\left( \frac{\pi}{P\; C} \right)} \right)}} & \left( {{Eq}.\mspace{14mu} 7} \right)\end{matrix}$For each pleat, the area on the downstream side that has pressure dropacross it is Ad₁ and Ad₂. Also from symmetry, Ad₁=Ad₂. Therefore thetotal area Atu of the upper end cap effected by the pressure drop isequal to the number of pleats×2×Ad₁:

$\begin{matrix}{{{Atu} = {2\left( {P\; C} \right)\left( {A\; d_{1}} \right)}}{or}{{Atu} = {\left( {\left( {P\; C} \right)\left( \frac{Di}{4} \right)({Do})\left( {{Sin}\left( \frac{180^{0}}{P\; C} \right)} \right)} \right) - \left( {\left( \frac{{Di}^{2}}{4} \right)(\pi)} \right)}}} & \left( {{Eq}.\mspace{14mu} 8} \right)\end{matrix}$

EXAMPLES Example 1 A Filter Cartridge with Conventional ID Seals

A filter cartridge configuration considered in this example is one whichis similar to FIG. 1, except it has two opposite open end caps similarto end cap 5, and has an outside pleat diameter (Do) of 4 inches; aninside pleat diameter (Di) of 2 inches; a pleat count (PC) of 40; and, apressure drop (AP or PD) across the media of 100 psid in use. A seal isprovided along the ID of each end cap.

Do=4; Di=2; number of pleats=40. Plugging these values into the aboveequation gives a total area on the upper end cap Atu=3.135 inches²

The total force (Ftu) acting in a negative axial direction (in directionof gravity) on the top end cap Ftu=−100 psid×AtuFtu=(−100×3.135)=−313.5 poundf (pounds of force)

With the conventional filter cartridge as defined 313.5 pounds of forceis acting on both the upper and lower end cap in opposite directions.The force (−) on the upper end cap is acting downward. The force (+) onthe lower end cap is acting upward. The net result is that the filtercartridge is experiencing a compressive force along its vertical axis of313.5 pounds. By design (in the conventional cartridge) the majority ofthis force is transmitted through the end caps to the inner liner. Themedia pack will experience a portion of this force because the force isdistributed over the areas Ad1 and Ad2 for each pleat. This distributionof force creates a bending moment on the end caps that transfers a smallportion of the total load to the media pack.

Example 2 Moving the Lower Seal to the Outside Diameter

Moving the seal from the inside diameter to the outside diameter changesthe magnitude and direction of the force acting on the lower end cap.Whereas in the conventional design discussed, the force on the lower endcap is in the upward or positive (+) direction, relocating the seal tothe outside diameter causes the force to act on the lower end cap in adownward or negative (−) direction. In addition, the area is larger andtherefore the force is larger.

Keep in mind that the pressure upstream of the media (Pu) is greaterthan the pressure downstream of the media (Pd). By examination of FIG. 7it can be concluded that Pu acts on the upper surface of the end capdefined by Au; and that Pd acts on the lower surface of the end capdefined by Au. Knowing that Pu>Pd indicates that the net force on Au foreach pleat is acting in the downward or negative (−) direction.

Areas Ad1 and Ad2 are on the downstream side of the media. By placingthe seal on the outside diameter of the lower end cap, the downstreampressure Pd now acts on both sides of the areas Ad1 and Ad2; therebycanceling each other out resulting in a net axial force of zero actingon those areas.

Using trigonometric equations and some of the equations derived earlier,one can find the area Au as a function of the known parameters Do, Diand the number of pleats.

Again using the equation for the area of a circular sector one knowsthat:

$\begin{matrix}{{{Au} + {A\; d_{1}} + {A\; d_{2}} + {A\; d_{3}} + {A\; d_{4}}} = \frac{(\pi)\left( {Do}^{2} \right)}{(4)\left( {P\; C} \right)}} & \left( {{Eq}.\mspace{14mu} 9} \right)\end{matrix}$Also, by symmetry we know:Ad ₁ =Ad ₂  (Eq. 10)We also have previously derived the equation for Ad1 (Eq. 7)

${A\; d_{1}} = {\left( {\left( \frac{Di}{8} \right)({Do})\left( {{Sin}\left( \frac{180^{0}}{P\; C} \right)} \right)} \right) - \left( {\left( \frac{{Di}^{2}}{8} \right)\left( \frac{\pi}{P\; C} \right)} \right)}$And from the equation for a circular sector we know that:

$\begin{matrix}{{{A\; d_{3}} + {A\; d_{4}}} = {\left( \frac{{Di}^{2}}{4} \right)\left( \frac{\pi}{P\; C} \right)}} & \left( {{Eq}.\mspace{14mu} 5} \right)\end{matrix}$

By substituting Eq. 5, 7, and 10 into Eq. 9, and solving for Au onegets:

$\begin{matrix}{{Au} = {\left( {\left( \frac{\pi}{4} \right)\left( \frac{{Do}^{2}}{P\; C} \right)} \right) - \left( {\left( \frac{Di}{4} \right)({Do})\left( {{Sin}\left( \frac{180^{0}}{P\; C} \right)} \right)} \right)}} & \left( {{Eq}.\mspace{14mu} 12} \right)\end{matrix}$

Using the dimensions from the previous example, except this time thelower end cap uses a seal on the outside diameter instead of the insidediameter:

Do=4; Di=2; number of pleats=40; Pressure differential or drop (PD)=100psid.

From the previous example, one knows that the total force acting in anegative axial direction (in direction of gravity) on the top end capFtu=−313.5 pounds.

By examination of FIG. 6, one can conclude that the pressure acting onthe lower end cap surfaces, for one pleat, upstream of the filter mediacombine to create a net force of Pressure drop×Au in a downward ornegative (−) direction. The pressure acting on the lower end capsurfaces, for one pleat, downstream of the filter media combine tocreate a net axial force of zero.

The total force acting on the lower end cap surfaces for all the pleatsis:Ftl=(−PD)(Au)(PC)

Using Eq. 12 one gets:

${Ftl} = {{\left( {- {PD}} \right)\left( {\left( \frac{\pi}{4} \right)\left( \frac{{Do}^{2}}{P\; C} \right)} \right)} - {\left( {\left( \frac{Di}{4} \right)({Do})\left( {{Sin}\left( \frac{180^{0}}{P\; C} \right)} \right)} \right)\left( {P\; C} \right)}}$Plugging in the Numbers:

${Ftl} = {{{\left( {- 100} \right)\left( {\left( \frac{\pi}{4} \right)\left( \frac{4^{2}}{40} \right)} \right)} - {\left( {\left( \frac{2}{4} \right)(4)\left( {{Sin}\left( \frac{180^{0}}{40} \right)} \right)} \right)(40)}} = {{- 629.0}\mspace{14mu}{poundf}}}$

The net surface force on the lower end cap, not counting the force fromthe upper end cap, with the seal on the outside diameter, is acting inthe opposite direction of the force that is acting on the lower end capof the conventional design. Also, the magnitude of the force is largerthan on the conventional design.

The net result is that the filter cartridge with the end cap using theseal on the outside diameter will be moved downward in the housing untilit is stopped.

Example 3 Locating Seal(s) at an Intermediate Location

It is noted that it is not necessary to have the seal on the lower endcap to be at the outside diameter of the end cap in order to achievethis downward force Ftl described earlier. All that is needed to obtaina downward force Ftl is enough downward force to ensure that the filtercartridge will bottom out on the bowl thereby positioning the upper endcap such that it can transfer the majority of the force Ftu on the upperend cap through the inner liner.

One approach would be to decrease the diameter of the seal on the lowerend cap such that the net axial forces on the lower end cap would bezero. The force on the upper end cap Ftu operating in a downwarddirection would ensure that the filter cartridge would bottom outagainst a bottom of the housing. Reducing the seal diameter furtherwould cause the net force to begin to increase in an upward direction.Continuing to reduce the seal diameter will eventually reach a pointwhere this diameter is the same diameter as the seal on the upper endcap, which would have axial forces the same as on a conventional filtercartridge. An electronic spreadsheet can be used to explore variousdiameters and forces to achieve a specific result.

Referring to FIG. 8 one can see that it is similar to FIG. 7 except thatan additional diameter Ds has been added. This is the seal diameter onthe lower end cap shown at a diameter other than at the outside orinside diameter. As a result the surface areas Ad1 and Ad2 (from FIG. 7)are now divided into three sections each A2, A6, & A8 for Ad1 and A3,A5, & A7 for Ad2.

The areas of interest are A2, A3, and A4. By inspection it can be seenthat upstream pressure, applied to A1, is outside the diameter Ds of theseal. This means that the pressure on both sides of A1 are the same andtherefore cancel each other out. This same condition, on the downstreamside, can be found for areas A5, A6, A7 & A8.

Again, by inspection one can see that the pressure on area A4 acts in adownward (−) direction with a magnitude of pressure drop×A4. Also, byinspection one can see that due to symmetry, A2=A3. And the pressure onA2 & A3 acts in an upward (+) direction with a magnitude each ofpressure drop×A2.

Through trigonometric equations one can find areas A4, A2, and A3 as afunction of: Ds, the seal diameter; Do, the outside diameter of themedia pack; Di, the inside diameter of the media pack; and, the numberof pleats.

To find area A4 one must first find the angles ∠a, ∠d, ∠c, & ∠b asillustrated in FIG. 8. ∠a has been found previously.

$\begin{matrix}{{\angle\; a^{0}} = \frac{180^{0}}{PC}} & \left( {{Eq}.\mspace{14mu} 2} \right)\end{matrix}$

From the Solutions of Oblique angled triangles one knows that:

${\angle\; d^{0}} = {\left( \frac{{Tan}^{- 1}\left( {\left( \frac{Di}{2} \right)\left( {{Sin}\;\angle\; a^{0}} \right)} \right)}{\frac{Do}{2}} \right) - \left( {\left( \frac{Di}{2} \right)\left( {{Cos}\;\angle\; a^{0}} \right)} \right)}$and ∠ c⁰ = 180⁰ − (∠ a⁰ + ∠ d⁰)and using the solutions of Oblique angled triangles:

${\angle\; b^{0}} = {180^{0} - \left( {{\angle\; c^{0}} + {{Sin}^{- 1}\left( {({Di})\left( \frac{{Sin}\;\angle\; c^{0}}{Ds} \right)} \right)}} \right)}$Again from the equation for the area of a circular sector one knowsthat:

$\begin{matrix}{{A_{4} + A_{7} + A_{8} + A_{11} + A_{12}} = {0.008727(2)\left( {\angle\; b^{0}} \right)\left( \frac{{Ds}^{2}}{4} \right)}} & \left( {{Eq}.\mspace{14mu} 14} \right)\end{matrix}$And from symmetry one knows that:A ₇ =A ₈; & A ₁₁ =A ₁₂Combining and solving for A4 one gets:

$\begin{matrix}{A_{4} = {\left( {{.008727}(2)\left( {\angle\; b^{0}} \right)\left( \frac{{Ds}^{2}}{4} \right)} \right) - \left( {2\left( {A_{8} + A_{12}} \right)} \right)}} & \left( {{Eq}.\mspace{14mu} 15} \right)\end{matrix}$From the Solutions of Oblique angled triangles one knows that:

$\begin{matrix}{{A_{8} + A_{12}} = {\left( \frac{Di}{2} \right)\left( \frac{Ds}{2} \right)\left( \frac{{Sin}\;\angle\; b^{0}}{2} \right)}} & \left( {{Eq}.\mspace{14mu} 16} \right)\end{matrix}$Substituting Eq. 16 into Eq. 15 one gets:

$A_{4} = {\left( {0.008727(2)\left( {\angle\; b^{0}} \right)\left( \frac{{Ds}^{2}}{4} \right)} \right) - \left( {2\left( \frac{Di}{2} \right)\left( \frac{Ds}{2} \right)\left( \frac{{Sin}\;\angle\; b^{0}}{2} \right)} \right)}$Reducing down one gets:A ₄=(0.004364(∠b ⁰)(Ds ²))−(0.25(Di)(Ds)(Sin ∠b ⁰))  (Eq.17)

From basic trigonometry one knows that the area of a section of a flatring described by an outside diameter (Do), an inside diameter (Di), andangle θ° describing the arc of the section, is:

$\begin{matrix}{{{Area} = {\left( \frac{\theta^{0}}{360^{0}} \right)\left( \frac{\pi}{4} \right)\left( {{Do}^{2} - {Di}^{2}} \right)}}{{Therefore}\text{:}}{{A_{1} + A_{2} + A_{3}} = {2\left( \frac{\angle\; a^{0}}{360^{0}} \right)\left( \frac{\pi}{4} \right)\left( {{Do}^{2} - {Di}^{2}} \right)}}} & \left( {{Eq}.\mspace{14mu} 18} \right)\end{matrix}$

-   -   and knowing that A₂=A₃, Eq. 18 becomes:

${A_{1} + {2\left( A_{2} \right)}} = {2\left( \frac{\angle\; a^{0}}{360} \right)\left( \frac{\pi}{4} \right)\left( {{Do}^{2} - {Ds}^{2}} \right)}$And solving for A₂:

$\begin{matrix}{A_{2} = {{\left( \frac{\angle\; a^{0}}{360^{0}} \right)\left( \frac{\pi}{4} \right)\left( {{Do}^{2} - {Ds}^{2}} \right)} - \left( \frac{A_{1}}{2} \right)}} & \left( {{Eq}.\mspace{14mu} 19} \right)\end{matrix}$And again from symmetry:A ₂ +A ₆ +A ₈ +A ₁₀ +A ₁₂ =A ₃ +A ₅ +A ₇ +A ₉ +A ₁₁  (Eq.20)Also from the equation of a circular arc:

$\begin{matrix}{{A_{1} + A_{2} + A_{3} + A_{4} + A_{5} + A_{6} + A_{7} + A_{8} + A_{9} + A_{10} + A_{11} + A_{12}} = {{.008727}(2)\left( {\angle\; a^{0}} \right)\left( \frac{{Do}^{2}}{4} \right)}} & \left( {{Eq}.\mspace{14mu} 21} \right)\end{matrix}$Applying Eq. 20 to Eq. 21 one gets:

$\begin{matrix}{{A_{1} + A_{4} + {2\left( {A_{2} + A_{6} + A_{8} + A_{10} + A_{12}} \right)}} = {{.008727}(2)\left( {\angle\; a^{0}} \right)\left( \frac{{Do}^{2}}{4} \right)}} & \left( {{Eq}.\mspace{14mu} 22} \right)\end{matrix}$From the Solutions of Oblique angled triangles we know that:

$\begin{matrix}{{A_{2} + A_{6} + A_{10} + A_{12}} = {\left( \frac{Di}{2} \right)\left( \frac{Do}{2} \right)\left( \frac{{Sin}\;\angle\; a^{0}}{2} \right)}} & \left( {{Eq}.\mspace{14mu} 23} \right)\end{matrix}$Applying Eq. 23 to Eq. 22 and solving for A₁:

$A_{1} = {{{.008727}\left( {\angle\; a^{0}} \right)\left( \frac{{Do}^{2}}{2} \right)} - A_{4} - {2\left( \frac{Di}{2} \right)\left( \frac{Do}{2} \right)\left( \frac{{Sin}\;\angle\; a^{0}}{2} \right)}}$Simplifying we get:A ₁=0.004364(∠a ⁰)(Do ²)−A ₄−0.25(Di)(Do)(Sin ∠a ⁰)  (Eq.24)Substituting Eq.24 into Eq. 19 and simplifying:

$\begin{matrix}{A_{2} = {{{.002182}\left( {\angle\; a^{0}} \right)\left( {{Do}^{2} - {Ds}^{2}} \right)} - \left( {{.002182}\left( {\angle\; a^{0}} \right)\left( {Do}^{2} \right)} \right) + \frac{A_{4}}{2} + \left( {{.125}({Di})({Do})\left( {{Sin}\;\angle\; a^{0}} \right)} \right)}} & \left( {{Eq}.\mspace{14mu} 25} \right)\end{matrix}$

Now both areas A2 and A4 are known in terms of known parameters (Do, Di,number of pleats). By inspection (FIG. 8) one knows that; A2=A3; thatthe upstream pressure Pu acts on the area A4, while the downstreampressure Pd acts on the areas A2 and A3; and that on the rest of theareas (A1, A5, A6, A7, and A8) the pressure on either side of the endcap is the same and therefore cancel each other out in the axialdirection.

In order to achieve a force balance on the end cap such that the nextaxial force is equal to zero, one must find a geometry such that:A ₂ +A ₃ =A ₄  (Eq.26)Since A2=A3, one can rewrite Eq. 26:2(A ₂)=A ₄  (Eq.27)Substituting Eq. 25 into Eq. 27 we get:0.004364(∠a ⁰)(Do ² −Ds ²)−(0.004364(∠a ⁰)(Do ²))+A ₄+(0.25(Di)(Do)(Sin∠a ⁰))=A ₄Rearranging the equation gives us:0.004364(∠a ⁰)((Do ²)−(0.004364(∠a ⁰)(Ds ²))−)(0.004364(∠a ⁰)(Do²)+(0.25)(Di)(Do)(Sin ∠a ⁰))=A ₄ −A ₄=0Reducing the equation:0.004364(∠a ⁰)(Ds ²)−(0.25(Di)(Do)(Sin ∠a ⁰)  (Eq.28)Recalling Eq. 2:

${\angle\; a^{0}} = \frac{180^{0}}{PC}$gives us the following equation:

${{.004364}\left( \frac{180^{0}}{PC} \right)\left( {Ds}^{2} \right)} = {{.25}({Di})({Do})\left( {{Sin}\left( \frac{180^{0}}{PC} \right)} \right)}$And solving Eq. 28 for Ds:

${Ds} = \sqrt{\frac{({Do})({Di})\left( {{Sin}\left( \frac{180^{0}}{PC} \right)} \right)}{{.017452}\left( \frac{180^{0}}{PC} \right)}}$Further simplifying the equation:

${Ds} = \sqrt{{.3183}({Do})({Di})\left( {{Sin}\left( \frac{180^{0}}{PC} \right)} \right)({PC})}$And recognizing that 0.3183 is the reciprocal of π:

$\begin{matrix}{{Ds} = \sqrt{({Do})({Di})\left( {{Sin}\left( \frac{180^{0}}{PC} \right)} \right)\left( \frac{PC}{\pi} \right)}} & \left( {{Eq}.\mspace{14mu} 29} \right)\end{matrix}$Solving Eq. 28 for Di:

$\begin{matrix}{{Di} = \frac{\pi\left( {Ds}^{2} \right)}{({PC})({Do})\left( {{Sin}\left( \frac{180^{0}}{PC} \right)} \right)}} & \left( {{Eq}.\mspace{14mu} 30} \right)\end{matrix}$Solving Eq. 28 for Do:

$\begin{matrix}{{Do} = \frac{\pi\left( {Ds}^{2} \right)}{({PC})({Di})\left( {{Sin}\left( \frac{180^{0}}{PC} \right)} \right)}} & \left( {{Eq}.\mspace{14mu} 31} \right)\end{matrix}$

For example, using the earlier dimensions of Do=4 inches, Di=2 inches,and number of pleats=40; applying Eq. 29:

${Ds} = {\sqrt{(4)(2)\left( {{Sin}\left( \frac{180^{0}}{40} \right)} \right)\left( \frac{40}{\pi} \right)} = {2.827\mspace{14mu}{inches}}}$In order to achieve a force balance on the end cap such that the netaxial force on the end cap is equal to zero, with a pleat pack outsidediameter (Do) of 4 inches; an inside diameter (Di) of 2 inches; andtotal number of pleats of 40, one would need a seal diameter (Ds) of2.83 inches. Thus, at 2.83 inches, for the system defined, Ds=Db. Thiswould be the diameter where the seal and the sealing surface makecontact.

With respect to the overall element, lab testing can be used to evaluatethe net axial load on the element. In particular, as an approach, a loadcell can be placed on the inside diameter of the filter cartridge. Oneend of the load cell would be attached to the upper end cap, the otherend attached to the lower end cap. The filter cartridge would be placedinto the filter housing. Oil, at a standard test flow, would passthrough the filter cartridge. Test dust or other contaminant would beinjected upstream of the filter cartridge. As the filter collects thetest duster contaminant, pressure drop across the filter would increase,thereby increasing the axial load in the filter cartridge. A filtercartridge using a standard sealing arrangement will generate an axialforce on the load cell. This force will increase in proportion of thepressure drop across the filter. A filter cartridge using the preferredseal arrangements characterized, would have resolved all or most of theaxial forces on the filter cartridge. This would be assessed, as thepressure drop would increase across the media, by observations ofrelatively little, if any, increase on the axial force of the load cell.

It is noted that the above formulations indicate the number of pleats asa variable in the formulation. As a practical matter, with typicalliquid cartridges, once the pleat population is sufficiently high, itsincrease does not substantially change the preferred location for Db.This is exemplified by the mathematical model plotted in FIG. 11. InFIG. 11, the number of pleats is plotted on the X axis, and the Y axisrepresents unit axial load. The dimensions refer to FIG. 10. It can beseen that above a pleat population of about 20, for example 20-30, thereis relatively little change in axial load, as the number of pleatschange. Referring to FIG. 10, arrow X indicates a direction of out-to-inflow or standard (std) flow. Arrow Y indicates a direction of in-to-outflow or reverse (rev) flow. Dimension Z indicates pleat depth.

These variables are identified in the graph on FIG. 11.

B. Design Approaches Using the Principles

The above principles allow one to create a coreless (no inner liner atall or none having capability to withstand an axial load above 20 lb.)filter cartridge which is not subject to excessive axial loads on themedia pack during filter loading. The following design guidelines assumethat the cartridge is open on both ends and that an inner liner forpleat support (radial) is part of the filter housing.

One can start with the outside diameter (Do) and inside diameter (Di) ofthe pleat pack and the pleat count (PC).

Using the following equation derived from the above calculations, theseal diameter (DsB) that will give an axial load of zero can becalculated:

${DsB} = \sqrt{\frac{({Do})({Di})\left( {{Sin}\left( \frac{180}{PC} \right)} \right)({PC})}{\pi}}$For example: Do=3.27 inches; Di=1.59 inches; PC=50

${DsB} = {\sqrt{\frac{(3.27)(1.59)\left( {{Sin}\left( \frac{180}{50} \right)} \right)(50)}{\pi}} = {2.28\mspace{14mu}{inches}}}$DsB represents the tube outside diameter that seals on the I.D. of theo-ring. Looking up this diameter in a catalogue for standard sizedo-rings (such as Parker Seals GL-10/91) indicates the closest tube O.D.to be 2.25 inches (page A5-5, o-ring size 2-035).

Depending upon the particular requirements one could choose to use thestandard 2-035 o-ring with a tube O.D. of 2.25 inches and accept someaxial load on the media pack. A second option would be to use thefollowing equations to calculate the proper dimensions of the cartridgehaving DsB=2.25 instead of 2.28.

To maintain an axial load of zero, use the standard o-ring 2-035, andkeep PC=50; and Di=1.59; the following equation calculates the new Do:

${Do} = \left( \frac{(\pi)\left( {Ds}^{2} \right)}{({PC})({Di})\left( {{Sin}\left( \frac{180}{PC} \right)} \right)} \right)$Plugging in the numbers gives:

${Do} = {\left( \frac{(\pi)\left( 2.25^{2} \right)}{(50)(1.59)\left( {{Sin}\left( \frac{180}{50} \right)} \right)} \right) = {3.19\mspace{14mu}{inches}}}$If, in the alternative, one wanted to keep PC=50; and Do=3.27; thefollowing equation calculates the new Di:

${{{Di} = \left( \frac{(\pi)\left( {Ds}^{2} \right)}{({PC})({Do})\left( {{Sin}\left( \frac{180}{PC} \right)} \right)} \right)};{{and}\mspace{14mu}{thus}}},{{Di} = {\left( \frac{(\pi)\left( 2.25^{2} \right)}{(50)(3.27)\left( {{Sin}\left( \frac{180}{50} \right)} \right)} \right) = {1.55\mspace{14mu}{inches}}}}$

If one wanted to keep the original media pack dimensions along with thestandard tube diameter (Do=3.27; Di=1.59; Ds0=2.25), the followingequation will calculate the amount of axial load (Fa) that will beapplied to the media pack. To do this one needs one more piece ofinformation; the pressure drop (PD) across the media pack. For thisexample 200 psid will be used (many hydraulic filter cartridges aredesigned to withstand up to 200 psid).Fa=(0.25)(PD)(π(Ds ²)−(PC)(Di)(Do)(Sin(180/PC)))Again, plugging in the numbers:Fa=(0.25)(200)(π(2.25²)−(50)(1.59)(3.27)(Sin(180/PC)))=−21.0 lbf (poundsof force)The minus (−) indicates the media pack is under compression.

As long as one stays at or above 20 pleats (PC ∃20), change in PC haslittle affect in any of the above equations.

It is also recognized that for any type of filter cartridge design,there is an annular area surrounding the media pack which is formed bythe outside diameter of the pleat pack and the inside diameter of thefilter housing (Gap 1). Since there can be more than one type of housingused for a given filter cartridge, there will be a range of gaps thatcan be used. This gap allows for some design flexibility in choosing thepleat pack O.D.

Therefore, when designing a filter cartridge using the described designapproach, one needs to take into account the flexibility this gap(Gap 1) provides.

Also, there is another annular gap that is critical to the structuralintegrity of the filter cartridge (Gap 2). This annular gap is formed bythe inside diameter of the media pack and the outside diameter of theliner. Under standard flow condition (fluid flowing radially inwardthrough the media pack), the primary job of the liner is to provideradial support to the media. As fluid flows through the media, thepressure drop across the media creates a force on the media that isdirected radially inward. The liner supports the media against theforce. If there is a gap between the I.D. of the media pack and the O.D.of the liner, the media pack will have to move the distance of the gapbefore the liner can provide any support. Because the media is somewhatflexible, a certain amount of gap is acceptable. If the gap becomes toolarge the media will flex too much and will prematurely fail.

Because of Gap 2 between the media and the liner, it is advisable tomaintain a minimum gap for any of the coreless cartridge designs. Thismeans defining an appropriate (Di) that relates to a properly sizedliner. As mentioned earlier, PC can be any number ∃20. Next, select aninitial Do based on the requirements needed for Gap 1. Then, using theabove equation for DsB, one can calculate the tube diameter for theseal.

Next, determine the maximum axial load (Fmax) that can be applied to themedia and use the following equation to calculate the maximum Do for afilter cartridge that has a fixed Di and DsB.

As an example, we shall use the information previously calculated.Di=1.59 inches; PC=50; and assume a Gap 1 which gives Do=3.27. Using theequation for DsB gives DsB=2.28.

Now lets assume a maximum axial load (Fmax) of −100 lbf at a pressuredrop (PD) of 200 psid.

${Do} = \frac{\left( {(\pi)\left( {{Ds}\; 0^{2}} \right)} \right) - \left( {(4)\left( \frac{F\;\max}{PD} \right)} \right)}{({PC})({Di})\left( {{Sin}\left( \frac{180}{PD} \right)} \right)}$Plugging in the numbers:

${Di} = {\frac{{(\pi)\left( 2.28^{2} \right)} - \left( {(4)\left( \frac{- 100}{200} \right)} \right)}{(50)(1.59)\left( {{Sin}\left( \frac{180}{50} \right)} \right)} = {3.67\mspace{14mu}{inches}}}$So for this design, (Do) can range from 3.27 to 3.67 without exceedingthe maximum acceptable axial load on the media pack of −100 lbf.

Attention is now directed to FIG. 14. In FIG. 14 a graph is presentedshowing a plot of Di vs. Do, for: a given pressure (PD) max (200 psig);defined acceptable force max on the filter cartridge (40 pounds offorce) a defined Ds; a defined pleat count; and a defined maximumeffective area that the pressure can differential can act upon, Ae. Thisfigure (Ae) of course would be zero, if the seal was specifically at Db.Thus, Ae is the amount of area the pressure differential can act upon tostay within the limited force range desired.

From the plot of FIG. 14, it can be seen that under the conditionsspecified there is an inverse relationship between Di and Do. Thus, ifthe intent is to increase Do, Di would be reduced, and vice versa.

Attention is now directed to FIG. 15. Here some examples of calculationsare shown, for fixed variables. The parameters are stated in the figure.

For the particular example evaluated, the pressure differential max isidentified as 200 psid, the force max acceptable on the filter cartridgeis 40 pounds of force.

The pleat count was fixed at 50, initially Do at 3.27 inches and Di at1.59 inches.

When this was the case, Ds was calculated as being at 2.28 inches, forDb.

The next several lines indicate how Do could be changed, and what itsultimate affect on the force. Do could be increased to 3.43 inches,maintaining Di and Ds fixed, with the force max going up to 40 pounds.Do could be decreased to 3.11 inches, with Di and Ds fixed, the forcemax changing to 40 pounds in the opposite direction.

The next two lines in the table show the effect of maintaining Do and Dsfixed, and moving Di. Di could be moved up to a maximum of 1.67, whilemaintaining the force and no higher than 40 pounds. Di could bedecreased to 1.51 inches, with a force going up to 40 pounds in theopposite direction.

The next two lines indicate how the seal Ds could be moved, with Do andDi figures fixed. The seal can be moved down to 2.22 inches, with theforce not exceeding the 40 pound range; and the seal could be moved upto 2.33 inches, with the seal not exceeding the 40 pounds.

Certain other figures in the table indicate relative percents from someof the calculations.

The lower table shows a calculation for an element having a differentsize assumed.

V. A Specific Example, FIGS. 12 and 13

In FIG. 12, an example filter cartridge employing principles accordingto the present disclosure is provided. The cartridge 500 comprisespleated media 501 extending between first and second opposite end caps502, 503. The particular construction is coreless, and has no inner coreor outer core. End cap 502 is open, with aperture 505 therein. End cap503 is also open. Projecting axially outwardly from cap 502 is sealsupport 506 with seal 507 thereon. Seal 507 is configured for radialsealing in an inward direction.

Axially projecting outwardly from end cap 503 is seal support 510 withseal 511 thereon. Seal 511 is also configured for sealing radiallyinwardly.

To create a balance in the sealing with: the outside pleat diameter (M)being 83.0 mm; the inside diameter of the pleats (N) being 40.5 mm, andthe pleat depth (O) being 21.3 mm; the seal diameter Ds (indicated at Q)is 57.9 mm, for each of seals 507, 511. In this instance Dscorresponding to Q, would be Db.

For the example shown, the pleat length is 279 mm.

Still referring to FIG. 12, the cartridge 500 further includes acontaminant and containment collection feature 530. The featurecomprises an extension 531 having media 532 therein. When the cartridge500 is installed, as it is removed liquid flow through media 532 filtersthe standing liquid in the cartridge. Principles relating to contaminantcontainment arrangements are described for example in PCT Publication WO02/081052, of Oct. 17, 2002, incorporated herein by reference.

In FIG. 13 cartridge 500 is shown installed in an overall filterarrangement 540 comprising a housing 541 secured to a filter head 542.Seal 507 is shown sealing to structure 545, in this instance a portionof an inner pipe or core arrangement 546. Seal 511 is shown secured to aportion of housing base 550. In this instance portion 550 is secured toa remainder of the housing 541 by bolts 542′. Thus, portion 550 is anadaptor positioned in housing 541, at a bottom thereof, to accommodateseal 511. Portion 550 also helps center cartridge 500 in housing 541,during installation.

VI. Selected General Observations Concerning Mechanical Structures;Assemblies; and, Methods

A. Mechanical Filter Cartridge Structures.

The present disclosure provides for a variety of alternateconfigurations for filter cartridges, from conventional ones. Preferredones have been previously described, in which one or more seal locationsare defined with respect to Db, or in general with respect to locationwere certain surface axial forces will result in use, in thecorresponding end cap.

In this section, some various additional or alternative mechanicalconstructions and features are characterized. These can be used,advantageously, to provide for desirable filter cartridges. However, notall are required to be used together, to obtain some benefit.

-   -   1. Provision of a closed end cap which nevertheless has an axial        seal support projecting axially outwardly therefrom, preferably        with a seal member thereon.    -   2. Provision of filter cartridge with at least one end cap        thereon, which has a radial seal support thereon, at a location        intermediate: (a) an outer location at an outer edge of the        media; and, (b) an inner location radially equal to a most        radially inward projection of media. Typically and preferably        the axially outwardly projecting support is located to support a        seal at a location at least 10% of the distance across the end        cap, (from outer pleat tip to the inner pleat tip) from either        pleat tip edge, typically at least 15% of that distance.    -   3. A filter cartridge with two end caps as described at 2 above.    -   4. A filter cartridge in accord with any of the above three        general characterizations, which has no inner axial load support        core.    -   5. A filter cartridge in accord with any of the above four        characterizations, which has no outer axial load support liner.

Based on the above principles, an approach to design of a filtercartridge for liquid system can be as follows:

1. Determine a ΔP across the filter media (max.) and capability of thefilter cartridge for accepting axial load (F max) for a given housingsystem with a diameter of a pleat tip support tube (which will establishDi) as well as maximum housing diameter (which will establish Do), theseal location Ds can be located to provide DsB (the balanced location)at a location with a range such that under normal operating conditions,F max will not be exceeded.

2. Similarly, each of the identified parameters can be treated as avariable with the others fixed or fixed over range, allowing for theirspecific calculation and preferred filter cartridge configurations.

Herein, an example was provided relating to a hydraulic filter whichthere was an assumed ΔP max with a 200 psid, as is typical for manyhydraulic filters. F max, the maximum amount of load the filtercartridge can accept would not be fixed in all instances, it would be afunction of the material chosen. For an example, a maximum force of −40lbf (pounds of axial force) was used for purposes of calculation;however higher or lower figures could be used, depending on the system.

For a lube system, we can expect different limits. ΔP max for many lubesystems would be lower than the 200 psid for hydraulic systems, forexample in the range of 100-150 psid. F max again would be a function ofthe materials chosen. It could be −40 lbf, but could have other valuesas well.

It is again noted that when the seal diameter is discussed herein, sealdiameter is meant to refer to the diameter of the interface between theseal ring and the corresponding housing component, when the cartridge isin place.

B. Assemblies.

Of course the present disclosure relates to overall filter assemblies,having cartridges as characterized herein within them. The overallfilter assemblies may be configured for top load or bottom load. Thefeatures of the assemblies may be in accord with the general featurescharacterized in the descriptions and/or examples above.

The liquid filter assemblies may, again, be configured, for example, asoil (lube) filters, fuel filters or hydraulic filters.

C. Methods of Assembly, Use and Servicing.

In general, methods of assembly and use are provided. The methods ofassembly generally involve configuring components in accord with thedescriptions herein. The methods of use generally involve directingliquid flow through a serviceable filter cartridge constructed in accordwith the principles described herein, with net effects as characterizedresulting. In some instances, a seal between the cartridge and thehousing base also provides for centering, during servicing.

VII. Additional Examples, FIGS. 16 and 17

A. Spin-on Assembly, FIG. 16.

The reference numeral 600, FIG. 16 generally indicates a liquid filterarrangement according to a further embodiment of the present disclosure.The arrangement 600 includes a filter head 601 and a removable liquidfilter assembly 602. The filter assembly 602 comprises an outer wall 603and an internal cartridge 604.

The particular liquid filter assembly 602 depicted, is a “spin-on”assembly, meaning that the componentry 602 is generally removed andreplaced during a service operation. That is, the cartridge 604 isgenerally received in the housing 603 such that when the housing 603 isdisconnected from the filter head 601, in use, servicing involvesreplacement of the liquid filter assembly 602 with a new housing 603 andnew cartridge 604, previously assembled together. That is, the cartridge604 is not removed from housing 603 during servicing.

Referring still to FIG. 16, the cartridge 604 comprises media 605, inthis instance pleated media 606 extending between first and secondopposite end caps 607, 608 respectively. End cap 608 is a closed endcap, shown supported on support structure 610 within bottom 611 ofhousing 603. The cartridge 604 includes an inner liner at 604 a.

End cap 607 is an open end cap, having flow aperture 615 therethrough.End cap 607 includes seal support arrangement 617 supporting o-ring seal618, for sliding over post 620 during installation, and sealing aroundpost 620 during use.

End cap 607 further includes outwardly projecting flange 625, which canbe in positioned to engage structure on housing 603, to inhibit removalof cartridge 604 from housing 603, after initial installation.

It is noted that the particular cartridge 604 depicted, is outer linerfree.

The seal 630 defined in this instance by o-ring 618 has a sealeddiameter Ds located, for example, at or near the balance point Db,discussed previously.

End cap 608, is supported against motion downwardly in the direction ofarrow 635, by supports 610.

Assembly 600 is configured for out-to-in flow, with flow of unfilteredliquid to be filtered into the head 601 occurring at 644, and thenthrough entry 643 into annulus 641 around filter cartridge 604. Theliquid would then filtered, by passage through the media 606 into innerregion 606 a. The filtered liquid would then flow into channel 620 a inhead 601, and outwardly through outlet flow exit 640.

Having an out-to-in flow pattern, will generate a higher upstreampressure region P_(u) versus a lower downstream pressure P_(d), on endcap 608, which will generally drive the end cap 608 upwardly, i.e.,opposite the direction of arrow 635.

Post 620 includes stop 645 thereon, which will be engaged by sealsupport arrangement 617, should the cartridge begin to slide in theopposite direction of arrow 635, under the biasing forces indicated.

On end cap 607, the location of seal 630, again, can be positionedessentially at a balance point D_(b), so there would be no upper ordownward forces from the liquid pressure differential on the end cap607, if desired. Alternatively, the seal 630 can be positionedalternately, within the range of locations around D_(b), as describedherein.

Still referring to FIG. 16, the particular method of engagement betweenassembly 602 and filter head 601 is through threaded engagement as shownat 650.

Of course spin-on assemblies analogous to assembly 602 could beconfigured for “in-to-out” flow, across the media pack 604, if desired.

B. An Alternate Liquid Filter Cartridge Arrangement, FIG. 17.

In FIG. 17, liquid filter arrangement 700 is depicted comprising afilter head 701, a removable housing 702 and a filter cartridge 703. Inthis instance, the cartridge 703 is a serviceable cartridge, that can beremoved and replaced by disconnecting housing 702 from head 701, atthreads 710, replacing the cartridge 703 within bowl 702, and thenremounting bowl 702 on head 701.

Seal 711, 712 are shown to inhibit leakage outwardly from bowl 702.

The cartridge 703 is shown configured for in-to-out flow, althoughalternate configurations are possible. The cartridge 703 comprises mediapack 714, in this instance comprising pleated media 714 a, extendingbetween upper end cap 715 and lower end cap 716. For the example shown,lower end cap 716 is closed. Around the media pack 714 is provided anouter support 718, which can comprise a coiled roving or liner, asdesired.

End cap 715 is open having central aperture 715 a. End cap 715 furtherincludes seal support 720 thereon, supporting seal member 721, in thisinstance comprising o-ring 721 a.

The cartridge 703 is positioned with seal member 721 sealed against post730 in which flow aperture 730 a is provided, in communication with openinterior 703 a of cartridge 703.

During a normal operation, liquid flow would enter through inlet 730 andhead 701, and be transported through conduit 730 a into open region 703a. The liquid would then be filtered upon passage through the media pack714 into outer annulus 735. The liquid, now filtered, would enterconduit 736 and head 701, and exit through liquid flow outlet 738.Assembly 700 includes a bypass valve arrangement 740 therein, allowingfor a liquid flow to bypass cartridge 703, should the cartridge 703become sufficiently occluded. The bypass valve 740 comprises a valvehead 741 maintained closing aperture 742 by biasing arrangement 743comprising in this instance a coiled spring 744.

The seal support 720 is shown positioned on end cap 715, at a locationappropriate to support the seal arrangement 721 and sealing against post730, at a location either corresponding to Db, or modified from Db asdescribed herein.

VIII. Further Regarding Approach to Liquid Filter Design

Based on the above principles, still further definitions regardingfilter design to take advantage of principles according to the presentdisclosure, have been developed. These are indicated herein with respectto FIGS. 18-32. In FIGS. 18-32, all linear dimension figures are ininches and all area figures are in square inches.

A. Data Presentation, FIGS. 18-26

In FIGS. 18-26, plots of selected data and calculated data, for liquidfilter arrangements utilizing variations and principles according to thepresent disclosure are provided. In reviewing the tables of FIGS. 18-26,the following definitions should be considered:

1. Column 1

In the first column labeled Do is provided a selected outside diameterof the pleat pack. The outside diameter of a pleat pack having pleatedmedia, is the diameter defined by the pleat tips. For the tables ofFIGS. 18-20 (Group 1), Do is ranged from 2.5 inches (63.5 mm) up to 5.5inches (139.7 mm) in 0.1 inch (2.54 mm) increments, herein these arecalled “Group 1.” In FIGS. 21-23, Do is ranged from 5.6 inch (142.2 mm)to 10 inch (254 mm) in 0.1 inch (2.54 mm) increments, herein these aresometimes called “Group 2.” In FIGS. 24-26, Do is ranged from 1.5 inch(38.1 mm) to 2.4 inch (61 mm) in 0.1 inch (2.54 mm) increments; theseare sometimes called “Group 3.”

The grouping of Group 1, Group 2 and Group 3, for the tables of FIGS.18-26, is a grouping based on selected outside diameter or size, forconsideration. The groups are not meant to be otherwise significantlydistinct. The transitions between the group (over a step of 0.1 inch(2.54 mm)) are not intended to be discounted. As discussed below inconnection with the graphs of FIGS. 26-32, the graphs can b consideredas continuous across all regions identified.

The groupings could be of some assistance in considering application ofthe techniques described herein, to liquid filter applications, sincethe groupings do generally relate to small, medium and large size filtercartridges.

2. Column 2

In the tables of FIGS. 18-26 the term Di stands for the inside diameterof an identified pleat pack. For pleated media this would typically bethe inside diameter defined by the pleat tips. In many filtercartridges, the optimum pleat depth is considered to be the outsidediameter (od or Do) divided by 4. Under such circumstances,Di=Do−(Do÷4). Or, alternately stated, Di=0.5×Do. For the tables of FIGS.18-26, this formulation was used to define Di for a given definition ofDo.

3. Column 3

In FIGS. 18-26, in column 3 the “Plt Dpth” stands for pleat depth. Ofcourse pleat depth is related to Do as previously defined. Thus, for theentries in the column entitled “Plt Dpth,” a calculation of (Do−Di)/2 isused.

4. Column 4

The fourth column in the table entitled “Plt Cnt” refers to the numberof pleats or pleat count, for the example. As previously discussedherein, once the pleat count has reached 20, in general addition ofstill more pleats does not change significantly the calculation of Db.Thus, for the examples analyzed in the tables of FIGS. 18-26, the pleatcount in all instances was set at 20.

5. Column 5

The next column in the tables of FIGS. 18-26 is termed “Gap.” The “gap”is a variable selected, for purposes of the calculations reported inFIGS. 18-26, as an amount that Do and Di will be varied against thefixed seal location of col. 6 for comparison discussed below.

For the data presentations in the tables, three sizes of gaps were used,to show data ranges. The sizes are “7%,” “12%,” and “22%.” The use ofthese figures, to develop calculated data for comparison, will beapparent from the definitions of further columns.

6. Column 6

The next column in the tables of FIGS. 18-26 is entitled either “Ds=Db(calculated)” or “Ds/calc.” This is an indication of where the seallocation would be if it was at a calculated balance point Db, for Do(col. 1), Di (col. 2), and pleat count 20 (col. 4) in accord with thedescriptions herein such that calculated forces on opposite sides of theend cap would be equal to each other. The calculation approach would bein accord with the descriptions previously provided herein, using theidentified Do, Di and pleat count. Of course, again, once pleat count is20 or higher, it is considered not to affect the equation when varied,substantially.

For each of the identified locations of Db, in the sixth column, theseal location when at Db is at a position spaced across the end cap fromeach pleat tip edge.

The location of Db, col. 6 would be the same for cartridge having Do(col. 1) and Di (col. 2) as defined, without regard to whether thecartridge is designed for in-to-out flow or out-to-in flow as discussedherein.

7. Column 7

The seventh column in the tables of FIGS. 18-26 is entitled “Do min.”The term Do min” is meant to indicate a variation in the cartridge ofthe identified line, in which Do has been reduced by the selected “Gap”of col. 6, even though Di and seal location (Ds) have remained fixed. Ingeneral Do min=(1−Gap)×Do. Thus, for the first line in the table of FIG.18, Do min=(1−0.07)(2.5); i.e., 0.93 (Do) or 2.33 inch.

8. Column 8

In the eighth column, Do min (col. 7) is stated as a percent of Db (col.6). That is, the value on the table is equal to Do min/Db.

9. Column 9

The ninth column, entitled “Do max,” is meant to indicate anothervariation in the cartridge diameter, in this instance by adding to Dothe value of “Gap.” Thus Do max=(1+Gap)×Do. For the first line in thetable of FIG. 18, Do max=(1+0.07)×2.5, i.e., 1.07 (2.5) or 2.68 inch.

10. Column 10

The tenth column reflects Do max (col. 9) as a % of Db (col. 6). Thusthe value given equals Do max/Db.

11. Column 11

The eleventh column is entitled “Di min.” It reflects a variation in Di,by using the value chosen for Gap. Thus Di min=(1−Gap)×Di. For the firstline in the table of FIG. 18, Di min=(1−0.07)×1.25; i.e., 0.93 (1.25) or1.16 inch.

12. Column 12

Column 12 is a report of Di min (col. 11) as a % of Db (col. 6). Thus,the values in column 12 for any given line comprise Di min/Db.

13. Column 13

Column 13 is entitled “Di max.” It is equal to the value of Di modifiedby addition of the Gap. In general Di max equal (1+Gap) times Di. Forthe first line of the table of FIG. 18, Di max=(1+0.07)×1.25; i.e., 1.07(1.25) or 1.34 inch.

14. Column 14.

Column 14 reflects Di max (col. 13) as a % of Db (col. 6). It is acalculated value of Di max/Db.

15. Column 15

Column 15 is entitled “Astd(Ds=Di,Do,Di).” It is the area of the definedend cap (Do (col. 1), Di (col. 2), plt. count (col. 4)) that would beeffected by axial load for a cartridge in which the seal is located onthe inside diameter (Ds=Di) of the pleat pack. Thus it is a calculatedeffected area (Ae) or (Astd) for a standard cartridge design with a sealon the inside of the pleat pack. The term “effected area” in thiscontext, is meant to refer to an amount (in terms of surface area on oneside of the cartridge) which is subject to a difference in pressure ofPu versus Pd. It is a figure that results from subtracting from thetotal area of one side of the end cap, an amount of area that is subjectto the same pressure on both sides, whether it be Pu or Pd. (In thecalculation, pleat count of 20 is used.)

The value of column 15 is a calculated value, using the functionsdescribed previously herein.

For a cartridge in which a seal is located at an inside diameter of thepleat pack and out-to-in flow, the resulting end cap is under a forcetoward the media pack. For the tables of FIGS. 18-26, this such a forceis represented by positive numbers.

Of course if the flow was in the opposite direction “in-to-out,” theabsolute value of the effected area would be the same, but the directionof force would be opposite.

16. Column 16

Column 16 entitled “Ae(Ds calc, Do min, Di min)” is the calculatedeffected area of the end cap when Ds=the value of column 6, and the endcap parameters are an outside pleat pack diameter at Do min (col. 7) andan inside pleat diameter at Di min (col. 11), with the seal located atthe calculated position of Db for Do and Di. This value in column 16,then, indicates how much variation in effected area (Ae) there has beenfrom a balanced location (Ae=0), if the seal is maintained at the samelocation as col. 6, but Do and Di are modified to Do min and Di min. Theabsolute value of this can be compared to the value of column 15, to seewhether the amount of total effected area (Ae) is smaller, and thusbetter, by comparison to a standard filter cartridge. When the valuereported is negative, the pressure is away from the pleat pack (when anout-to-in flow is assumed). In the calculation, a pleat count of 20 isused.

17. Column 17

Column 17 entitled “Ds1=Ds as a function of Do min & Di min,” is afigure called Ds1, which, for the calculations presented in the table,corresponds to a location for a seal at which balance (Ae×0) would occur(a new calculated Db), if the cartridge had an outside diameter Do min(col. 7) and an inside diameter Di min (col. 11) and a pleat count of20.

18. Column 18

Column 18 entitled “Ds1 as a % of Db” is a statement of a calculation ofDs1 (column 17) as a percent of Db (column 6).

19. Column 19

Column 19 entitled “Ae(Ds calc, Do min, Di max” is the effected area(Ae) of the end cap when the seal is at the location Db (of column 6),but the pleat pack outside diameter is at Do min (col. 7), the insidediameter is a Di max (col. 13) and the pleat count is 20.

20. Column 20

Column 20 is entitled “Ds1=Ds as a function of Do min & Di max” is acalculated seal diameter balance point (Ae=0), for a cartridge in whichthe outside diameter is at Do min (col. 7), the inside diameter is at Dimax (col. 13) and the pleat count is 20.

21. Column 21

Column 21 entitled “Ds1 as a % of Db” is a statement of Ds1 (Col. 20) asa percentage of Db (column 6).

22. Column 22

Column 22 entitled “Ae(Ds calc, Do max, Di min” is the effected area(Ae) of the end cap when the seal is located at Db (column 6), but thepleat pack outside diameter is at Do max (col. 9), the inside diameteris at Di min (col. 17) and the pleat count is 20.

23. Column 23

Column 23 entitled “Ds1=Ds as a function of Do max & Di min” is acalculation of where the seal will be located to be in balance (Ae=0),for a media pack with an outside diameter at Do max (col. 9), an insidediameter at Di min (col. 11) and a pleat count of 20.

24. Column 24

Column 24 is a statement of the calculated seal location of column 23,as a percent of the Db value of column 6.

25. Column 25

Column 25 entitled “Ae(Ds calc, Do max, Di max” is the effected area(Ae) of the end cap when a seal is located at Db (column 6) and thecartridge has a pleat pack outside diameter of Do max (col. 9), a pleatpack inside diameter of Di max (co. 13) and a pleat count of 20.

26. Column 26

Column 26 entitled “Ds1=Ds as a function of Do max & Di max” is thecalculated seal location for a balance (Ae=0), for an end cap of Do max(col. 9), Di max (col. 13) and a pleat count of 20.

27. Column 27

Column 27 is a calculated value of the seal side of column 26 divided bythe value of Db in column 6.

Columns 28-31, allow for comparison of effected area for each of thefour variations in Do and Di (pleat count=20) previously discussed,against a standard cartridge for which the seal is located on the insidediameter, as is typical for many standard arrangements.

28. Column 28

Column 28 entitled “Ae(Ds=Db, Do min, Di min) % Astd” compares theeffected area (Ae) of an end cap using the seal at Db (col. 6) for amedia pack having Do min (col. 7), Di min (col. 11) and pleat count 20as defined, against the effected area of an end cap (same dimensions andpleat count) using a seal located at Di min (i.e., at the insidediameter) which would be standard (Astd).

For example: for a cartridge with Ds=2.89 inches; Do=3.20 inches;Di=1.60 inches; and a pleat count of 20; the effected area (Ae) is 2.57square inches as compared to 3.27 square inches for a correspondingstandard style cartridge with the same Do, Di but with Ds=Di. The areaAe is 79% of Astd. This means that the axial load is also 79% of theaxial load on the corresponding standard filter cartridge.

29. Column 29

Column 29 is entitled “Ae(Ds=Db, Do min, Di max) % Astd,” and provides asimilar comparison to col. 28, in this instance where the effected area(Ae) is calculated for a seal at Db (col. 6), and the pleat dimensionsat Do min and Di max, against a similar cartridge with a seal located atthe inside pleat diameter.

For example: for a cartridge with Ds=2.89 inches; Do=3.20 inches;Di=2.50 inches; and a pleat count of 10; the effected area (Ae) is 0.32square inches as compared to 3.27 square inches for a correspondingstandard filter cartridge having the same Do, Di but with Ds=Di. Thearea Ae is 10% of Astd. This means that the axial load is also 10% ofthe axial load on the corresponding standard filter cartridge.

30. Column 30

Column 30 is entitled “Ae(Ds=Db, Do max, Di min) % Astd,” and provides asimilar comparison (to col. 28, 29) of effected area (Ae) to effectedarea standard (Astd), where the seal is at Db (column 6) and the pleatdimensions are: outside dimension at Do max, and inside dimension at Dimin. The comparison of Ae is against the same cartridge, but with a seallocated at the inside diameter (Astd).

For example: for a cartridge with Ds=2.89 inches; Do=5.00 inches;Di=1.60 inches; and a pleat count of 20; the effected area (Ae) is 0.32square inches as compared to 3.27 square inches for a correspondingstandard filter cartridge of the same Do, Di but with Ds=Di. The area Aeis 10% of Astd. This means that the axial load is also 10% of the axialload on the corresponding standard filter cartridge.

31. Column 31

Column 31 is entitled “Ae(Ds=Db, Do max, Di max) % Astd,” and is asimilar comparison of effected areas to cols. 28-30, for a situation inwhich the seal would be located at Db (column 6) but the outside pleatdiameter would be at Do max and the inside pleat diameter Di max. Thecomparison would be of effected area (Ae) for such a situation, againstan effected area (Astd) of the same end cap but with the seal at theinside diameter.

For example: for a cartridge with Ds=2.89 inches; Do=5.00 inches;Di=2.50 inches; and a pleat count of 20; the effected area (Ae) is 3.21square inches as compared to 3.27 square inches for a correspondingstandard style cartridge of the same Do, Di but with Ds=Di. The area Aeis 98% of Astd. This means that the axial load is also 98% of the axialload on the corresponding standard style cartridge.

The comparisons of columns 28-31, allow an understanding of what percentof axial load (Ae) is left on the end cap, when the end cap is adjustedto have the dimensions and seal location identified in the particularexample, by comparison to a standard style end cap in which the seal isprovided at the inside diameter of the pleat tips, as opposed to spacedacross the end cap between the inside diameter of the pleat tips and theoutside diameter of the pleat tips, in accord with the definitionsprovided. For the examples of these four columns, the cartridge has notbeen optimized to obtain Ae=0. Thus the comparison of interest,indicates how much actual reduction in Ae and thus pressure, hasoccurred.

B. Selected Data Plots, FIGS. 27-32

Attention is now directed to the graphs of FIGS. 27-32. In FIGS. 27-32,the groups refer to groups of seal diameter (Ds) resulting from the dataof FIGS. 18-26.

1. FIGS. 27 and 28

-   -   (a) FIG. 27

Referring first to the graph of FIG. 27, the graph includes a plot ofcertain information included in tables of FIGS. 18-20.

In particular, for the systems described in the tables of FIGS. 18-20,the plot of FIG. 27 is of the seal diameter Ds against Di. Seven linesare plotted. The lines are identified as A, B, C, D, E, F and G asfollows:

Line A=for data in FIG. 20 a plot of the Ds value of column 6 (x-axis)against a Di value corresponding to Di min, column 11 (y-axis).

Line B=a plot for the data in FIG. 19 of the Ds value of column 6(x-axis) against a Di value corresponding to Di min, column 11 (y-axis).

Line C=a plot for data of FIG. 18 of the Ds value of column 6 (x-axis)against a Di value corresponding to Di min, column 11 (y-axis).

Line D=a plot from any of FIGS. 18-20 of the Ds value of column 6(x-axis) against a Di value corresponding to Di, column 2 (y-axis).

Line E=a plot from FIG. 18 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

Line F=a plot from FIG. 19 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

Line G=a plot from FIG. 20 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

-   -   (b) FIG. 28

For the systems described in the tables of FIGS. 18-20, the plot of FIG.28 is of the seal diameter Ds against Do. Seven lines are plotted. Thelines are identified as A1, B1, C1, D1, E1, F1 and G1 as follows:

Line A1=for data in FIG. 20 a plot of the Ds value of column 6 (x-axis)against a Do value corresponding to Do min, column 7 (y-axis).

Line B1=a plot for the data in FIG. 19 of the Ds value of column 6(x-axis) against a Do value corresponding to Do min, column 7 (y-axis).

Line C1=a plot for data of FIG. 18 of the Ds value of column 6 (x-axis)against a Do value corresponding to Do min, column 7 (y-axis).

Line D1=a plot from any of FIGS. 18-20 of the Ds value of column 6(x-axis) against a Do value corresponding to Do, column 2 (y-axis).

Line E1=a plot from FIG. 18 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

Line F1=a plot from FIG. 19 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

Line G1=a plot from FIG. 20 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

2. FIGS. 29 and 30

-   -   (a) FIG. 29

For the systems described in the tables of FIGS. 21-24, the plot of FIG.29 is of the seal diameter Ds against Di. Seven lines are plotted. Thelines are identified as A2, B2, C2, D2, E2, F2 and G2 as follows:

Line A2=for data in FIG. 23 a plot of the Ds value of column 6 (x-axis)against a Di value corresponding to Di min, column 11 (y-axis).

Line B2=a plot for the data in FIG. 22 of the Ds value of column 6(x-axis) against a Di value corresponding to Di min, column 11 (y-axis).

Line C2=a plot for data of FIG. 21 of the Ds value of column 6 (x-axis)against a Di value corresponding to Di min, column 11 (y-axis).

Line D2=a plot from any of FIGS. 21-23 of the Ds value of column 6(x-axis) against a Di value corresponding to Di, column 2 (y-axis).

Line E2=a plot from FIG. 21 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

Line F2=a plot from FIG. 22 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

Line G2=a plot from FIG. 23 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

-   -   (b) FIG. 30

For the systems described in the tables of FIGS. 21-23, the plot of FIG.30 is of the seal diameter Ds against Do. Seven lines are plotted. Thelines are identified as A3, B3, C3, D3, E3, F3 and G3 as follows:

Line A3=for data in FIG. 23 a plot of the Ds value of column 6 (x-axis)against a Do value corresponding to Do min, column 7 (y-axis).

Line B3=a plot for the data in FIG. 22 of the Ds value of column 6(x-axis) against a Do value corresponding to Do min, column 7 (y-axis).

Line C3=a plot for data of FIG. 21 of the Ds value of column 6 (x-axis)against a Do value corresponding to Do min, column 7 (y-axis).

Line D3=a plot from any of FIGS. 21-23 of the Ds value of column 6(x-axis) against a Do value corresponding to Do, column 2 (y-axis).

Line E3=a plot from FIG. 21 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

Line F3=a plot from FIG. 22 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

Line G3=a plot from FIG. 23 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

3. FIGS. 31 and 32

-   -   (a) FIG. 31

For the systems described in the tables of FIGS. 24-26, the plot of FIG.31 is of the seal diameter Ds against Di. Seven lines are plotted. Thelines are identified as A4, B4, C4, D4, E4, F4 and G4 as follows:

Line A4=for data in FIG. 26 a plot of the Ds value of column 6 (x-axis)against a Di value corresponding to Di min, column 11 (y-axis).

Line B4=a plot for the data in FIG. 25 of the Ds value of column 6(x-axis) against a Di value corresponding to Di min, column 11 (y-axis).

Line C4=a plot for data of FIG. 24 of the Ds value of column 6 (x-axis)against a Di value corresponding to Di min, column 11 (y-axis).

Line D4=a plot from any of FIGS. 24-26 of the Ds value of column 6(x-axis) against a Di value corresponding to Di, column 2 (y-axis).

Line E4=a plot from FIG. 24 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

Line F4=a plot from FIG. 25 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

Line G4=a plot from FIG. 26 of the Ds value of column 6 (x-axis) againsta Di value corresponding to Di max, column 13 (y-axis).

-   -   (b) FIG. 32

For the systems described in the tables of FIGS. 24-26, the plot of FIG.32 is of the seal diameter Ds against Do. Seven lines are plotted. Thelines are identified as A5, B5, C5, D5, E5, F5 and G5 as follows:

Line A5=for data in FIG. 26 a plot of the Ds value of column 6 (x-axis)against a Do value corresponding to Do min, column 7 (y-axis).

Line B5=a plot for the data in FIG. 25 of the Ds value of column 6(x-axis) against a Do value corresponding to Do min, column 7 (y-axis).

Line C5=a plot for data of FIG. 24 of the Ds value of column 6 (x-axis)against a Do value corresponding to Do min, column 7 (y-axis).

Line D5=a plot from any of FIGS. 24-26 of the Ds value of column 6(x-axis) against a Do value corresponding to Do, column 2 (y-axis).

Line E5=a plot from FIG. 24 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

Line F5=a plot from FIG. 25 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

Line G5=a plot from FIG. 26 of the Ds value of column 6 (x-axis) againsta Do value corresponding to Do max, column 9 (y-axis).

Utilization of the graphs of FIGS. 26-32 will be apparent from thefollowing example.

1. In many instances, the seal diameter for a system will be fixed bythe equipment. Consider for example an effort to design a new filtercartridge to fit on the head 601 of FIG. 16. Head 601 would already bein place on equipment, or would already have been designed to be inplace on that equipment. The seal diameter would be fixed, by the designof post 620, on the head 601.

In designing the replacement part 602, in particular the cartridge 604,then, the parameter of the seal diameter (Ds) would already be fixed.

Also, the overall outside and inside diameters of the housing 603 aregenerally fixed, or at least limited. This sets the range in which onecan design Do and Di for the cartridge.

2. If one assumes, for purposes of example, that the size range of theseal, Ds, for FIG. 16 is between 1.7 and 3.9 inches, the tables of Group1, FIG. 27 and FIG. 28, are appropriate for utilization. (Other sizes ofDs would involve Group 2 or Group 3.)

3. The line identified as “D” in FIG. 27 and “D1” in FIG. 28, identifiesfor any given seal diameter (Ds) in the range stated, appropriate Di andDo values, to achieve balance, i.e., to obtain Ae=0. That is, if oneassumes for example a seal diameter identified by the post 620 of 2.6inches, in FIG. 27 this indicates that to obtain a balance (Ae=0), a Diof a little more than 1.8 inches should be chosen, and from FIG. 28, aDo of about 4 inches should be chosen. (Actual values are incorresponding data charts.)

4. Of course it would be preferred to optimize the design, in manyinstances, to provide for Ae=0, in accord with the discussion of point 3above. However this is not, in all instances, practical or required.

The lines represented by line segment A in FIG. 27 and the line segmentA1 in FIG. 28, generally indicates lower useable limits for Di and Do,respectively, for given values of Ds. It can be seen from thecalculations of the tables, for FIG. 20, that as long as the valueselected for Di and Do, for a given Ds, is on or above lines A and A1respectively, substantial reduction in Ae, and thus corresponding load,result (by comparison to a standard seal design assumed to be with Dsbeing approximately Di).

5. In general, the line represented by line segments G and G1, FIGS. 17,28, reflect the extreme of Do max, Di max, col. 31, FIG. 20. This isgenerally a value Di, Do for a given selection Ds, that would be sogreat, as to not result in substantial advantage relative to a standardstyle cartridge, where Ds is located at approximately Di.

6. On the other hand, the line represented by line segments F and F1,generally reflect values for Di and Do respectively, for a givenselected Ds, whereat substantial reduction in Ae and thus forces occur.Thus, Di and Do, respectively, should be on or below lines of which Fand F1, respectively, are segments.

7. As a result, a general advantage will be achieved provided, for agiven value Ds, the values of Di and Do respectively are selected to beno less than the values given for lines represented by segments A andA1, and no more than the values given by lines represented by segments Fand F1.

8. Greater advantage results, when the values chosen for Di and Dorespectively, for a given Ds, are: (a) no less than the values of linesrepresented by segments B and B1 respectively; and, (b) no greater thanthe values of lines represented by segments F and F1 respectively; and,(c) preferably no greater than the values of lines represented by E andE1 respectively.

9. In typical applications of the principles herein, it will bepreferred that the values selected for Di and Do, for a given Ds, willbe no less than the values of lines represented by segments C and C1respectively. Also, preferably they are no greater than the values oflines represented by segments E and E1 respectively.

10. The graph of FIG. 27, as indicated previously, is central portion ofa continuous graph generated by FIG. 31 on the low end for Ds and FIG.29 on the high end for Ds. Thus: lines A, A2 and A4 are sections of acontinuous line; lines B, B2 and B4 are sections of a continuous line;lines C, C2 and C4 are sections of a continuous line; lines D, D2 and D4are sections of a continuous line; lines E, E2 and E4 are sections of acontinuous line; lines F, F2 and F4 are sections of a continuous line;and, lines G, G2 and G4 are sections of a continuous line.

11. Similarly, the graph of FIG. 28, as indicated above, is a centralsection of a continuous graph comprising FIGS. 28, 30 and 32. Thus,lines A1, A3 and A5 are sections of a continuous line; lines B1, B3 andB5 are sections of a continuous line; lines C1, C3 and C5 are sectionsof a continuous line; lines D1, D3 and D5 are sections of a continuousline; lines E1, E3 and E5 are sections of a continuous line; lines F1,F3 and F5 are sections of a continuous line; and, lines G1, G3 and G5are sections of a continuous line.

12. The graphs of FIGS. 27-32, then, can be used to select a preferredDs value range and Do value range, for a given Ds, over a Ds (sealdiameter) range of 1.06 inches (26.9 mm) to 7.06 inches (179 mm). Thedifferent lines indicate useable defined ranges, for effects (Ae) asdescribed in the tables. Typically the ranges selected for Di and Dorespectively, for a given Ds, will be on or between lines for whichsegments A (or A1) and F (or F1) are a part, typically on or betweenline of which B (or B1) and F (or F1) are a part, and often on orbetween lines of which segments C (or C1) and E (or E1) are a part.

IX. General Summary of Selected Principles According to the PresentDisclosure

A. General Features.

Techniques according to the present disclosure can be applied in avariety of liquid filter arrangements. The liquid filter arrangementsgenerally comprise media extending between first and second opposite endcaps. The media would typically be pleated, defining an inner pleatdiameter (Di) and an outer pleat diameter (Do). One or both of the endcaps can have an open central aperture.

In general at least one of the end caps would have a seal supportpositioned on a projection extending axially outwardly from the end cap(in a direction away from the media). In typical examples, the sealsupported by the seal support, is an o-ring, although alternatives arepossible. The seal can be supported to be directed inwardly oroutwardly. The o-ring or alternate seal, would generally define a sealdiameter Ds.

The filter cartridge can be used as a serviceable filter cartridge, inwhich it is removed and replaced from a housing during use. It also canbe contained permanently within a housing, to be replaced with thehousing part, during servicing.

The typical seal support shown in the drawings herein, is of a typewhich slides into position over (or inside of) a liquid filter assemblycomponent during use. In the examples, the seal supports are shown slidover a post or other structure, through which an aperture, or flowconduit extends. In some arrangements the seal support can slide insideof a flow aperture, to seal against the wall defining the flow aperture,in use.

Seal supports of the type shown in the descriptions herein, aregenerally put in position without an external clamp, such as a hoseclamp or similar structure, to secure the seals in place. Sucharrangements will sometimes be described herein as “non-clamp” or“non-clamping” seal supports or seal arrangements, or by similar terms.

The principles of the present disclosure can be utilized to providearrangements that have no inner liner and/or no outer liner, if desired.

The techniques according to the present disclosure can be utilized forarrangements that are configured for in-to-out flow, or out-to-in flow.Examples of both are described.

Techniques according to the present disclosure can be applied in systemsin which the pleated media includes, on one or both sides thereof,pleated media support, such as a pleated wire mesh support or a pleatedplastic mesh support.

The principles of the present disclosure, relate to preferred seallocations, to accomplish various effects.

B. Location of the Seal Diameter for Given End Cap of a Liquid FilterCartridge, at a Balance Point Db (Ae=0) or within a Desired Range ofthat Location.

In one aspect of the present disclosure, at least the first end cap of aliquid filter arrangement has a first central aperture therethrough, theseal support is positioned on the first end cap to define seal diameterDs, the seal diameter is within the range of 0.85-1.15 DbA, inclusive,typically within the range of 0.9-1.1 DbA inclusive, and preferablywithin the range of 0.95-1.05 DbA inclusive, wherein DbA is a diameterin which no axial surface force on the first end cap (A) toward or awayfrom the second end cap (B) in use, results. DbA, of course, is alocation which would define effective area of 0 (Ae=0) for theidentified end cap, in accord with the calculations above.

Of course in some applications of this aspect of the disclosure, bothend caps can be provided apertures therein, and both end caps can beprovided with seals thereon within a similar definition. Thus on thesecond end cap (B) there would be provided a seal support for a sealmember having a seal diameter DsB within the range of 0.85-1.15 DbB,typically 0.9-1.1 DbB and often within the range of 0.95-1.05 DbB.

C. Provision of a Liquid Filter Arrangement in which a Seal Location isPositioned Spaced from an Outer Diameter of the End Cap and Outer PleatTips, and Spaced From an Inner Diameter of the End Cap and Inner PleatTips.

Another aspect of defining liquid filter cartridges according to thepresent disclosure, will be understood to be that the filter cartridgeis such that at least on a first end cap having a central aperture, sealsupport is provided that is spaced across the end cap, from the insidediameter of the pleat tips (and end cap aperture if present) a distancecorresponding to at least 0.1X, where X is the dimension correspondingto the distance between the outside diameter of the pleat tips (or endcap outer perimeter if similar) and the inside diameter of the pleattips (or end cap aperture if similar and present).

For such situations, typically the seal arrangement is also positionedon the end cap a distance spaced from the outer pleat tip diameter (orend cap outer perimeter if similar), inwardly, a distance alsocorresponding to at least 0.1X.

In some arrangements, a similar definition can be provided for thesecond end cap, whether open or closed. That is, a seal arrangement canbe mounted on the second end cap defining a seal diameter spacedoutwardly from the inside pleat diameter (or aperture) and inwardly fromthe outside pleat diameter (or end cap perimeter) a distancecorresponding to at least 10% of the difference between the inside pleatdiameter (or aperture) and outside pleat diameter (or aperture).

In general, in some liquid filter cartridges, the end cap aperturediameter of an open end cap, will be approximately the same as (or onlyslightly smaller than) the inner pleat tip diameter. Also in someinstances the outside end cap diameter would be about the same as theoutside pleat diameter. However variations are possible.

When variations are used, the spacing should typically be consideredwith respect to the pleat tip inner diameter and outer diameter, sincethese factors control Ae.

D. Liquid Filter Cartridges with the Seal Location Spaced a SpecifiedAmount from the Inner Pleat Tips and Outer Pleat Tips.

In another aspect of the invention, the liquid filter cartridge isprovided with advantage, over a liquid filter cartridge in which theseal is provided on either the inside pleat diameter or the outsidepleat diameter, by having the seal supported at a location spaced fromboth the side pleat diameter and outside pleat diameter a distance of atleast 5 mm, typically at least 10 mm, and usually at least 15 mm.

E. Filter Defined with Respect to Effected Area.

In general it is preferred to provide a filter cartridge having at leastone end cap, and in some instances two end caps, defined with respect toseal position thereon, such that the seal position provides for a valueof Ae (effected area) of no more than 80%, typically no more than 55%,and usually no more than 20%, of a value for Ae of similar end cap andpleat tip definition (Do and Di) but in which the seal is located in thestandard position at approximately the inside pleat diameter (Ds=Di).

F. Filter Cartridge Defined with Respect to Defined Ds Selection of Do,Di, Through the Utilization of Plots of FIGS. 17-32.

In still another aspect of the techniques described herein, a filtercartridge, typically with a pleat count of 20 or greater, can beconstructed which has first and second end caps and pleated mediaextending therebetween, defining an inner pleat tip diameter (Di) and anouter pleat tip diameter (Do) for a given Ds located spaced between theDi and Do location, wherein: for a given value Ds within the range of1.06 inches (26.9 mm) to 7.06 inches (179.3 mm);

(a) from a plot of Ds (x-axis) versus Do (y-axis) Do is no less than avalue defined by a line extending from Ds, Do of 1.06 inches, 1.32inches (26.9 mm, 33.5 mm) to Ds, Do of 7.06 inches, 8.8 inches (179 mm,224 mm); and Do is no greater than a value defined by a line extendingfrom Ds, Do of 1.06 inches, 1.68 inches (26.9 mm, 42.7 mm); to Ds, Do of7.06 inches, 11.20 inches (179 mm, 284 mm); and

(b) from a plot of Ds (x-axis) versus Di (y-axis), Di is no less than avalue defined by a line extending from Ds, Di of 1.06 inches, 0.66inches (26.9 mm, 16.8 mm) to Ds, Di of 7.06 inches, 4.4 inches (179 mm,112 mm) and Di is no greater than a value defined by a line extendingfrom Ds, Di of 1.06 inches, 0.84 inches (26.9 mm, 21.3 mm) to Ds, Di of7.06 inches, 5.6 inches (179 mm, 142 mm).

Typically:

(a) from a plot of Ds (x-axis) versus Do (y-axis) Do is no less than avalue defined by a line extending from Ds, Do of 1.06 inches, 1.4 inches(26.9 mm, 290 mm) to Ds, Do of 7.06 inches, 9.3 inches (17.9 mm, 236mm); and Do is no greater than a value defined by a line extending fromDs, Do of 1.06 inches, 1.4 inches (26.9 mm, 35.6 mm); to Ds, Do of 7.06inches, 10.7 inches (179 mm, 272 mm); and

(b) from a plot of Ds (x-axis) versus Di (y-axis), Di is no less than avalue defined by a line extending from Ds, Di of 1.06 inches, 0.7 inches(26.9 mm, 17.8 mm) to Ds, Di of 7.06 inches, 4.65 inches (179 mm, 118mm) and Di is no greater than a value defined by a line extending fromDs, Di of 1.06 inches, 0.8 inches (26.9 mm, 20.3 mm) to Ds, Di of 7.06inches, 5.35 inches (179 mm, 135.9 mm).

Of course a variety of alternate preferred ranges be defined using suchplots, as explained above with respect to the graphs of FIGS. 17-32.

G. Liquid Filter Assemblies.

Of course techniques described herein can be utilized to develop liquidfilter assemblies comprising housings with filter cartridges therein(serviceable or otherwise). In general the housing would be configuredto support the filter cartridge, and the filter cartridge would beselected in accord with the general principles discussed herein, forexample as indicated above in Sections IX A-F.

H. Methods of Filtering.

Advantages result from liquid filtering operation in which the liquid tobe filtered is passed through an assembly in accord with those of IX Gabove. The advantages result from the advantageous on one or more endcaps of the filter cartridge.

It is noted that in many instances herein, a reference is made to astandard in which the seal is located at the inner pleat diameter, i.e.,Ds=Di. For purposes of the calculation, it was assumed that a standardwas Ds−Di. In some actual prior instances, there may have been a minorvariation from this.

What is claimed:
 1. A liquid filter cartridge comprising: (a) first andsecond, opposite, end caps; (i) at least the first end cap having afirst central aperture therethrough; and, (b) an extension of pleatedfilter media secured to, and extending between, the first and second endcaps; (i) the extension of pleated filter media defining an open centralvolume in fluid flow communication with the first central aperture; (ii)the media comprising a total of at least 20 pleats; (c) a first sealarrangement on the first end cap positioned to provide a larger sealdiameter (D_(s)A) when sealing than a diameter of the first centralaperture; the first seal arrangement comprising a radially directedseal; (i) D_(s)A being within the range of 0.92-1.08 D_(b)A inclusive,wherein D_(b)A is a calculated seal diameter at which no net surfaceaxial force on the first end cap toward or away from the second end capdue to liquid pressures against the opposite surfaces of the first endcap, in use, results, with D_(b)A calculated assuming that any pressuredrop across the media occurs at the media center line and is a stepfunction and that each media pleat assumes a triangular shape the sameas each other pleat.
 2. A liquid filter cartridge according to claim 1including: (a) a first seal support projecting outwardly from the firstend cap and having the first seal arrangement thereon.
 3. A liquidfilter cartridge according to claim 2 wherein: (a) the first sealarrangement comprises a first radially outwardly directed seal.
 4. Aliquid filter cartridge according to claim 3 wherein: (a) the firstradially outwardly directed seal comprises on an o-ring seal.
 5. Aliquid filter cartridge according to claim 4 wherein: (a) the liquidfilter cartridge has an axial load coreless construction.
 6. A liquidfilter cartridge according to claim 5 wherein: (a) the liquid filtercartridge has an axial load outer liner free construction.
 7. A liquidfilter cartridge according to claim 3 wherein: (a) the liquid filtercartridge has an axial load outer liner free construction.
 8. A liquidfilter cartridge according to claim 3 wherein: (a) the liquid filtercartridge has an axial load coreless construction.
 9. A liquid filtercartridge according to claim 2 wherein: (a) the first seal arrangementcomprises on an o-ring seal.
 10. A liquid filter cartridge according toclaim 1 wherein: (a) the first seal arrangement comprises an o-ringseal.
 11. A liquid filter cartridge according to claim 1 wherein: (a)the first seal arrangement comprises a radially outwardly directed seal.12. A liquid filter cartridge according to claim 2 wherein: (a) thefirst seal arrangement comprises a radially inwardly directed seal. 13.A liquid filter cartridge according to claim 12 wherein: (a) the firstseal arrangement comprises on an o-ring seal.
 14. A liquid filtercartridge according to claim 1 wherein: (a) the second end cap is aclosed end cap.
 15. A liquid filter cartridge according to claim 1wherein: (a) the second end cap is an open end cap.
 16. A liquid filtercartridge according to claim 15 wherein: (a) the second end cap includesa second seal arrangement comprising a radially directed seal.
 17. Aliquid filter cartridge according to claim 16 wherein: (a) the secondseal arrangement comprises a radially outwardly directed seal.
 18. Aliquid filter cartridge according to claim 16 wherein: (a) the secondseal arrangement comprises a radially inwardly directed seal.
 19. Aliquid filter cartridge according to claim 16 wherein: (a) a second sealsupport is positioned on the second end cap; (i) the second sealarrangement being positioned on the second seal support.
 20. A liquidfilter cartridge according to claim 19 wherein: (a) the second sealarrangement is positioned to provide a larger seal diameter (D_(s)B)with structure in a filter assembly when sealing than a diameter of thesecond central aperture; (i) D_(s)B being within the range of 0.85-1.15D_(b)B, inclusive, wherein: D_(b)B is a calculated seal diameter atwhich no net surface axial force on the second end cap toward or awayfrom the first end cap due to liquid pressure against the oppositesurfaces of the second end cap results, with D_(b)B calculated assumingthe any pressure drop across the media occurs at the media center lineand is a step function and that each media pleat assumes a triangularshape the same as each other pleat.
 21. A liquid filter cartridgeaccording to claim 20 wherein: (a) D_(s)B is within the range of0.92-1.08 D_(b)B, inclusive.
 22. A liquid filter cartridge according toclaim 20 wherein: (a) D_(s)B is within the range of 0.95-1.05 D_(b)B,inclusive.
 23. A liquid filter cartridge according to claim 16 wherein:(a) the second seal arrangement is positioned to provide a larger sealdiameter (D_(s)B) with structure in a filter assembly when sealing thana diameter of the second central aperture; (i) D_(s)B being within therange of 0.85-1.15 D_(b)B, inclusive, wherein: D_(b)B is a calculatedseal diameter at which no net surface axial force on the second end captoward or away from the first end cap due to liquid pressure against theopposite surfaces of the second end cap results, with D_(b)B calculatedassuming the any pressure drop across the media occurs at the mediacenter line and is a step function and that each media pleat assumes atriangular shape the same as each other pleat.
 24. A liquid filterassembly comprising: (a) a filter housing; (i) the filter housing beingthreaded, for mounting on a filter head, in use; and, (b) a liquidfilter cartridge positioned within the housing, the liquid filtercartridge comprising: (i) first and second, opposite, end caps; (A) thefirst end cap having a first central liquid flow aperture therethrough;and, (ii) an extension of filter media secured to, and extendingbetween, the first and second end caps; (A) the extension of filtermedia comprising pleated media defining an open central volume in fluidflow communication with the first central aperture and having a pleatinner diameter and a pleat outer diameter; and, (B) the media comprisinga total of at least 20 pleats; (iii) a first cartridge seal arrangementcomprising a first radially directed seal; and, (iv) the first cartridgeseal arrangement being positioned to provide a larger seal diameter(D_(s)A), when sealing, than a diameter of the first central aperture;(A) DA being within the range of 0.92-1.08 D_(b)A inclusive, whereinD_(b)A is a calculated seal diameter at which no net surface axial forceon the first end cap toward or away from the second end cap due toliquid pressures against the opposite surfaces of the first end cap, inuse, results, with D_(b)A calculated assuming the any pressure dropacross the media occurs at the media center line and is a step functionand that each media pleat assumes a triangular shape the same as eachother pleat.
 25. A liquid filter assembly according to claim 24including: (a) a filter head including an inlet channel; and, an outletchannel; (i) the outlet channel being defined by a liquid flow portionof the filter head; and, (b) the filter housing being secured to thefilter head with the first cartridge seal arrangement sealed to thefilter head.